Yokogawa AQ6380 User Manual

User ’s
Manual

AQ6380
Optical Spectrum Analyzer

IM AQ6380-01EN

2nd Edition

Thank you for purchasing the AQ6380 Optical Spectrum Analyzer. This is an instrument that can
quickly measure optical characteristics of devices, such as LD, LED light sources, and optical
amplifiers. It also has a touch screen and a zoom feature to make it easier to use.
This user’s manual explains the features, operating procedures, and handling precautions of the
instrument. To ensure correct use, please read this manual thoroughly before operation. Keep this
manual in a safe place for quick reference.
The manuals for this instrument are listed on the next page. Please read all manuals.

Contact information of Yokogawa offices worldwide is provided on the following sheet.

Document No. Description

PIM 113-01Z2 List of worldwide contacts

Notes

• The contents of this manual are subject to change without prior notice as a result of
improvements to the instrument’s performance and functionality. Refer to our website to view our
latest manuals.

• The figures given in this manual may differ from those that actually appear on your screen.

• Every effort has been made in the preparation of this manual to ensure the accuracy of its
contents. However, should you have any questions or find any errors, please contact your
nearest YOKOGAWA dealer.

• Copying or reproducing all or any part of the contents of this manual without the permission of
YOKOGAWA is strictly prohibited.

Trademarks

• Microsoft, Internet Explorer, MS-DOS, Windows, Windows 7, Windows 8.1, and Windows 10 are
registered trademarks or trademarks of Microsoft Corporation in the United States and/or other
countries.

• Adobe and Acrobat are either registered trademarks or trademarks of Adobe Systems
Incorporated.

• In this manual, the ® and TM symbols do not accompany their respective registered trademark
or trademark names.

• Other company and product names are trademarks or registered trademarks of their respective
holders.

Revisions

• 1st Edition: October 2021

• 2nd Edition: February 2024

2nd Edition: February 2024 (YMI)
All Rights Reserved, Copyright © 2021 Yokogawa Test & Measurement Corporation

IM AQ6380-01EN

i

Manuals

The following manuals, including this one, are provided as manuals for this instrument. Please read
all manuals.

Manuals Included with the Product

Manual Title Manual No. Description

AQ6380
Optical Spectrum Analyzer Getting Started
Guide

Request to Download AQ6380 Manuals IM AQ6380-73Z2 Describes the manuals provided on the

Optical Spectrum Analyzer IM AQ6360-92Z1 A document for China.
Safety Instruction Manual IM 00C01C01-01Z1 A document for the EU.

Manuals Provided on the Website

Download the following manuals from our website.

Manual Title Manual No. Description

AQ6380
Optical Spectrum Analyzer
User’s Manual

AQ6380
Optical Spectrum Analyzer Remote Control
User’s Manual

For details on downloading manuals, see Request to Download AQ6380 Manuals (IM AQ6380­73EN).
The “EN”, “Z1”, and “Z2” in the manual numbers are the language codes.

IM AQ6380-02EN This manual is provided in print. This

guide explains the handling precautions,
installation procedure, basic operations,
and specifications of this instrument.

website.

IM AQ6380-01EN This manual. Explains all functions and

operating procedures of the AQ6380
except remote control and program
functions.

IM AQ6380-17EN Explains functions for controlling

the instrument with communication
commands and program functions.

Online help

The User’s Manual (IM AQ6380-01EN) is incorporated in this instrument as help files. For
instructions on how to use the help, see section 9.7 in the User’s Manual, IM AQ6380-01EN.

ii

IM AQ6380-01EN

Conventions Used in This Manual

Prefixes k and K

Prefixes k and K used before units are distinguished as follows:

k: Denotes 1000. Example: 12 kg, 100 kHz
K: Denotes 1024. Example: 720 KB (file size)

Displayed characters

Bold characters in procedural explanations are used to indicate panel keys that are used in the
procedure and menu items that appear on the screen.

Notes

The notes and cautions in this manual are categorized using the following symbols.

Improper handling or use can lead to injury to the user or damage to the

instrument. This symbol appears on the instrument to indicate that the user must
refer to the user’s manual for special instructions. The same symbol appears in
the corresponding place in the user’s manual to identify those instructions. In the
manual, the symbol is used in conjunction with the word “WARNING” or “CAUTION.”

WARNING

CAUTION

Note

Calls attention to information that is important for the proper operation of the

Calls attention to actions or conditions that could cause serious or fatal injury to

the user, and precautions that can be taken to prevent such occurrences.

Calls attention to actions or conditions that could cause light injury to the user or

damage to the instrument or user’s data, and precautions that can be taken to
prevent such occurrences.

instrument.

IM AQ6380-01EN

iii

Contents

Manuals ........................................................................................................................................... ii

Conventions Used in This Manual ................................................................................................... iii

Chapter 1 Features

1.1 Measuring the Optical Spectrum .................................................................................... 1-1

1.2 Displaying Optical Spectral Waveforms ....................................................................... 1-19

1.3 Analyzing the Optical Spectrum ................................................................................... 1-36

1.4 Saving and Loading Data ............................................................................................. 1-51

1.5 System Setup ............................................................................................................... 1-53

1.6 Application Feature (APP Feature) .............................................................................. 1-57

Chapter 2 Setting the Measurement Conditions

2.1 Measurement Wavelength (Frequency) Range ............................................................. 2-1

2.2 Wavelength Resolution ................................................................................................ 2-12

2.3 Sampling ...................................................................................................................... 2-15

2.4 Measurement Sensitivity .............................................................................................. 2-17

2.5 Level scale ................................................................................................................... 2-23

2.6 Sub Scale ..................................................................................................................... 2-32

2.7 Noise Reduction ........................................................................................................... 2-38

Chapter 3 Measuring the Optical Spectrum

3.1 Measurement Precautions ............................................................................................. 3-1

3.2 Continuous Light Measurement (CW) ............................................................................ 3-4

3.3 Pulse Light Measurement .............................................................................................. 3-9

3.4 Measurement Using External Triggers ......................................................................... 3-18

3.5 Trigger Output .............................................................................................................. 3-22

3.6 Analog Out ................................................................................................................... 3-23

Chapter 4 Displaying Optical Spectral Waveforms

4.1 Zooming the Waveform Display ..................................................................................... 4-1

4.2 Holding the Waveform Display ....................................................................................... 4-7

4.3 Holding the Maximum or Minimum Waveform Display................................................... 4-9

4.4 Averaging the Waveform Display ................................................................................. 4-10

4.5 Calculating the Waveform Display ............................................................................... 4-12

4.6 Normalizing the Waveform Display .............................................................................. 4-18

4.7 Curve Fitting the Waveform Display ............................................................................. 4-19

4.8 Displaying Power Spectral Density Waveforms ........................................................... 4-25

4.9 Searching Waveforms .................................................................................................. 4-26

4.10 Copying and Clearing Waveforms................................................................................ 4-34

4.11 Noise Mask .................................................................................................................. 4-36

4.12 Highlighting the Waveform Display .............................................................................. 4-38

Chapter 5 Displaying Measured Values and Calculated Values Using Markers

5.1 Wavelength and Level Values of Optical Spectrum ....................................................... 5-1

5.2 Wavelength/Level Difference between Optical Spectra ............................................... 5-10

5.3 Power Spectral Density ................................................................................................ 5-13

5.4 Integral Power Value .................................................................................................... 5-16

iv

IM AQ6380-01EN

Contents

Chapter 6 Analyzing Optical Spectral Waveforms

6.1 Specifying an Analysis Range ........................................................................................ 6-1

6.2 Spectral Width (THRESH, ENVELOPE, RMS, PEAK RMS, NOTCH) ........................... 6-4

6.3 SMSR ............................................................................................................................. 6-8

6.4 Power ........................................................................................................................... 6-10

6.5 Light Source (DFB-LD, FP-LD, LED) ........................................................................... 6-12

6.6 ITLA .............................................................................................................................. 6-16

6.7 WDM Signals (WDM, WDM SMSR) ............................................................................. 6-19

6.8 Gain and Noise Figure of Optical Amplifiers ................................................................ 6-25

6.9 Optical Filter Characteristics Measurement ................................................................. 6-31

6.10 Measurement of Level Fluctuations in Single- Wavelength Light (0 nm Sweeping) .... 6-42

6.11 Editing the Grid Table ................................................................................................... 6-45

6.12 Analysis Data Logging ................................................................................................. 6-47

Chapter 7 Saving and Loading Data

7.1 USB Storage Devices .................................................................................................... 7-1

7.2 Saving and Loading Waveform Data.............................................................................. 7-2

7.3 Saving and Loading Waveform Data (All Trace) .......................................................... 7-12

7.4 Saving Analysis Data ................................................................................................... 7-18

7.5 Saving and Loading Setting Data ................................................................................. 7-23

7.6 Saving Screen Capture Data ....................................................................................... 7-27

7.7 File Operations ............................................................................................................. 7-31

1

2

3

4

5

6

Chapter 8 Useful Applications

8.1 Overview of the Application Feature .............................................................................. 8-1

8.2 Installing and Uninstalling Applications .......................................................................... 8-2

8.3 WDM Test ....................................................................................................................... 8-4

8.4 FP-LD Test ..................................................................................................................... 8-9

8.5 DFB-LD Test ................................................................................................................. 8-12

8.6 LED Test ....................................................................................................................... 8-15

8.7 Optical Fiber End Face Check ..................................................................................... 8-17

8.8 Exporting Maintenance Information ............................................................................. 8-19

Chapter 9 System Setup

9.1 Registering User-Defined Menus ................................................................................... 9-1

9.2 Locking the Keys ............................................................................................................ 9-2

9.3 Measurement Items ....................................................................................................... 9-4

9.4 Display Items .................................................................................................................9-11

9.5 Ethernet Communication .............................................................................................. 9-15

9.6 Sounding the Buzzer .................................................................................................... 9-21

9.7 Displaying Manuals with the Help Feature ................................................................... 9-22

9.8 Viewing the System Information ................................................................................... 9-23

9.9 Resetting the Instrument to Its Factory Default Settings .............................................. 9-26

7

8

9

App

Index

IM AQ6380-01EN

v

Contents

Appendix

Index

Appendix 1 Grid Table for WDM Wavelength ........................................................................App-1

Appendix 2 Data Calculation Algorithms for Spectrum Widths ............................................. App-2

Appendix 3 Details of Each Analytical Function .................................................................. App-11

Appendix 4 WDM Analysis Function ................................................................................... App-24

Appendix 5 Optical Amp Analysis Function ......................................................................... App-39

Appendix 6 Optical Filter Analysis Function ........................................................................ App-43

Appendix 7 Function Menu Tree Diagram ........................................................................... App-60

vi

IM AQ6380-01EN

Chapter 1 Features

1.1 Measuring the Optical Spectrum

Measurement range

Set the measurement wavelength (frequency) range as follows:

• Combination of the center wavelength (Center) and sweep span (Span)

• Combination of the measurement start wavelength (Start) and stop wavelength (Stop)

Sweep span

Start
wavelength

Optical power

Center
wavelength

Wavelength

Stop wavelength

Reference level

You can set the wavelength and
frequency scale display using the
horizontal scale (SETUP >
Horizontal Scale) settings.

1

Features

AUTO

CENTER

SWEEP

SETUP

MARKER

USER

REMOTE

UNDO/

LOCAL

FUNCTION

REPEAT SINGLE

SPAN

RESOLN

ZOOM

PEAK

SEARCH

SYSTEM

PRT

HELP

SCN

STOP

LEVEL

SENS

TRACE

ANALYSIS

FILE

APP

PRESET

CENTER

Set the center wavelength, start
wavelength, stop wavelength, etc.

SPAN

Set the sweep span, start
wavelength, stop wavelength, etc.

SETUP

Set the wavelength and frequency
scale, etc.

IM AQ6380-01EN

1-1

1.1 Measuring the Optical Spectrum

Level scale

Set the level scale of the waveform display. The level scale unit can be switched between log scale
(dBm) and linear scale (e.g., mW).

Optical power

You can set the log and
linear scale using the
vertical scale (LEVEL)
settings.

FUNCTION

REPEAT SINGLE

AUTO

CENTER

SWEEP

SETUP

MARKER

USER

REMOTE

UNDO/
LOCAL

RESOLN

ZOOM

SEARCH

SYSTEM

HELP

SPAN

PEAK

PRT
SCN

STOP

LEVEL

SENS

TRACE

ANALYSIS

FILE

APP

PRESET

Wavelength

LEVEL

Set the reference level, log and
linear scale, etc.

1-2

IM AQ6380-01EN

Peak

Optical power

Wavelength

1.1 Measuring the Optical Spectrum

Wavelength resolution

The wavelength resolution expresses the bandwidth of a monochromator’s filter characteristics. It
is defined as the wavelength span between two points 3 dB down from the peak wavelength of the
spectrum when a narrow linewidth light source such as a gas laser is measured. You can select
the resolution setting from the following available settings: 0.005 nm, 0.01 nm, 0.02 nm, 0.05 nm,

0.1 nm, 0.2 nm, 0.5 nm, 1 nm, and 2 nm. Or, you can set it to any value between 0.01 nm and

2.00 nm (Custom).

Note

The wavelength resolution has wavelength bands in which the resolution setting and the actual resolution
do not match. For example, if the resolution is set to 0.005 nm, the actual resolution is about 0.005 nm at
the wavelength of 1550 nm and 0.007 nm at the wavelength of 1310 nm.
When the wavelength resolution is set between 0.01 nm and 2 nm, the resolution setting and the actual
resolution are almost the same.

3 dB

1

Features

AUTO

CENTER

SWEEP

SETUP

MARKER

USER

REMOTE

UNDO/

LOCAL

Wavelength

FUNCTION

REPEAT SINGLE

SPAN

RESOLN

ZOOM

PEAK

SEARCH

SYSTEM

PRT

HELP

SCN

STOP

LEVEL

SENS

TRACE

ANALYSIS

FILE

APP

PRESET

resolution

The RESOLN key is a shortcut key for
displaying the Resolution menu of the
SETUP menu. You can use either key
to set the resolution.

RESOLN

Resolution setting

SETUP -> Resolution

Resolution setting

IM AQ6380-01EN

1-3

Sweep span

Sampling points

Sampling
interval

1.1 Measuring the Optical Spectrum

Sampling points and sampling interval

Sampling points refer to the number of data points measured (sampled) within the set sweep span
(span). You can set this value in the range of 101 to 200001 on this instrument. Sampling interval
refers to the wavelength spacing of sampling data.
If you decrease the sampling points, you may be able to measure in a shorter time.

AUTO

CENTER

SWEEP

SETUP

MARKER

USER

REMOTE

UNDO/
LOCAL

Optical power

FUNCTION

REPEAT SINGLE

PRT
SCN

LEVEL

TRACE

ANALYSIS

SPAN

RESOLN

ZOOM

PEAK

SEARCH

SYSTEM

HELP

Wavelength

Resolution
setting

STOP

SENS

SETUP

Sampling points, sampling interval

FILE

APP

PRESET

1-4

Note

If the sampling interval is large (the sampling points are small) relative to the set measurement resolution,
the measured spectrum may become inaccurate, such as peaks missing from the spectrum.
In such cases, the letters “UNCAL” will appear in the waveform display area to indicate that the
measurement conditions are inappropriate. In normal cases, set the sampling points to AUTO.
For details on UNCAL and sampling interval, see page 1-14.

IM AQ6380-01EN

1.1 Measuring the Optical Spectrum

Measurement sensitivity

This instrument has two measurement sensitivity modes: TRAD and RAPID. You can set the mode
with the Sensitivity Mode key. Setting this mode sets the operation mode of the analog amplifier
circuit built into the instrument.

• RAPID mode

This sensitivity mode is specialized for high-speed measurement of CW light. Select the
sensitivity setting from six levels: RAPID1 to RAPID6.

• TRAD mode

This sensitivity mode can measure both CW light and pulsed light. It operates in the same way
as the conventional sensitivity mode of YOKOGAWA’s optical spectrum analyzers.
Select the sensitivity setting from seven levels: N/HOLD, N/AUTO, NORMAL, MID, HIGH1,
HIGH2, and HIGH3.

If you select N/HOLD, the analog amplifier circuit is set to fixed gain. The gain is set based on
the Reference Level setting in the LEVEL menu. If fixed gain is selected, there is a limit on the
effective measurement range. The range is from “the reference level –20 dBm” to “the reference
level +10 dBm.”

If you select a setting other than N/HOLD, the analog amplifier circuit is set to auto gain. This
mode allows a wider range of levels to be measured in a single sweep.

1

Features

For settings other than N/HOLD, you can select double speed mode, which measures at a
sweep speed that is about twice as fast as usual. For sensitivities in double speed mode, “(x2)”
is indicated in the sensitivity setting name such as MID(x2) and NORMAL(x2).
Double speed mode is suitable for measuring light sources such as LED light sources where the
change in the spectral level is relatively gradual. It also has the following features.

• Double speed mode has a noise level about 2 dB higher than normal mode.

• If you use double speed mode under UNCAL conditions, for spectral waveforms that

have sudden changes, such as those produced by a DFB-LD, the level and wavelength
measurement accuracies may degrade. Use it after checking the measurement spectrum.

FUNCTION

REPEAT SINGLE

AUTO

CENTER

SWEEP

SETUP

MARKER

USER

SPAN

RESOLN

ZOOM

PEAK

SEARCH

SYSTEM

STOP

LEVEL

SENS

TRACE

ANALYSIS

FILE

SENS

Measurement sensitivity

SETUP

Measurement sensitivity

IM AQ6380-01EN

UNDO/
LOCAL

REMOTE

HELP

PRT
SCN

APP

PRESET

1-5

1.1 Measuring the Optical Spectrum

Correlation diagram between measurement sensitivity and sweep speed

[TRAD mode] [RAPID mode]

Sweep speed:
normal

Sweep speed:
normal x 2

Sweep speed:
rapid

N/HOLD

Low

Measurement sensitivity

High

(Fixed gain)

N/AUTO

NORMAL

MID

HIGH1

HIGH2

HIGH3

N/AUTO(x2)

NORMAL(x2)

MID(x2)

HIGH1(x2)

HIGH2(x2)

HIGH3(x2)

RAPID1

Fast

RAPID2

RAPID3

Sweep speed

RAPID4

RAPID5

RAPID6

Slow

Noise reduction

This instrument has two types of averaging functions that you can use: averaged measurement and
roll-averaged measurement.

• Averaged measurement (Average Times)

• Roll-averaged measurement (Roll Average)

Averaged measurement

Sampling is performed multiple times at each sample point during sweeping, and spectral data
is obtained from the average values. The average times value is set using Average Times on the
SETUP menu.
Averaging cannot be selected when, on the SETUP menu, the measurement sensitivity is set to
NORMAL(x2) of TRAD mode.

Sampling interval

Optical power

Wavelength

Averages the specified number of times and
then moves to the next sampling position

1-6

IM AQ6380-01EN

1.1 Measuring the Optical Spectrum

Roll-averaged measurement

In roll-averaged measurement, the set measurement range (SPAN) is swept multiple times. Each
sweep is averaged with the previous measurement data to update the waveform.
Roll-averaged measurement is set using Roll Average on the TRACE menu.

Sweeps repeatedly the specified number of times

Optical power

Wavelength

Performs averaging every sweep and updates the waveform

FUNCTION

REPEAT SINGLE

AUTO

CENTER

SPAN

STOP

LEVEL

1

Features

SWEEP

SETUP

MARKER

USER

REMOTE

UNDO/

LOCAL

RESOLN

ZOOM

PEAK

SEARCH

SYSTEM

HELP

PRT
SCN

SENS

TRACE

ANALYSIS

FILE

APP

PRESET

TRACE->Roll Average

Rolling average

SETUP->Average Times

Average times

IM AQ6380-01EN

1-7

1.1 Measuring the Optical Spectrum

Starting a measurement (sweep)

When you start a measurement, the instrument sweeps the set measurement range and measures
the spectrum.

FUNCTION

AUTO

CENTER

SWEEP

REPEAT SINGLE

SPAN

RESOLN

STOP

LEVEL

SENS

Press these keys to control sweeping directly.

AUTO Auto sweep
REPEAT Repeat sweep
SINGLE Single sweep
STOP Stop sweep

SETUP

MARKER

USER

REMOTE

UNDO/
LOCAL

ZOOM

PEAK

SEARCH

SYSTEM

HELP

PRT
SCN

TRACE

ANALYSIS

FILE

APP

PRESET

SWEEP

Auto sweep, repeat sweep, single sweep, stop sweep

1-8

IM AQ6380-01EN

1.1 Measuring the Optical Spectrum

Function menus

CENTER key

“Measurement range” in Features

Center wavelength and center frequency (Center)

This is the center of the measurement range. The specified value is displayed in the center of
the waveform display area.
The unit of values (wavelength or frequency) is set using Horizontal Scale on the SETUP
menu.

Start wavelength and start frequency (Start)

This is the start point of the measurement range. The specified value is displayed at the left
end of the waveform display area.
The unit of values (wavelength or frequency) is set using Horizontal Scale on the SETUP
menu.

Stop wavelength and stop frequency (Stop)

This is the stop point of the measurement range. The specified value is displayed at the right
end of the waveform display area.
The unit of values (wavelength or frequency) is set using Horizontal Scale on the SETUP
menu.

1

Features

Note

• If you change the measurement range start point (Start) or measurement range stop point (Stop),
the measurement range center (Center) and sweep span (Span) will change.

• If you change the measurement range center (Center), the sweep span (Span) will not change.

Setting the center of the measurement range to the peak wavelength of the waveform
(Peak WL -> Center)

The center wavelength of the measurement range is set to the peak waveform of the trace (A
to G) selected using Active Trace on the TRACE menu.

IM AQ6380-01EN

1-9

1.1 Measuring the Optical Spectrum

Setting the center of the measurement range to the center wavelength of the waveform
(Mean WL -> Center)

The center of the measurement range is set to the waveform of the trace (A to G) selected
using Active Trace on the TRACE menu (the wavelength of the center position between
two points that are lower by the threshold value (20 dB) from the peak value of the center
wavelength).

Optical power

Wavelength

Auto setting of the center wavelength (Auto Center)

For each sweep, the measurement center wavelength (Center WL) is set to the peak
wavelength of the waveform of the trace (A to G) selected using Active Trace on the TRACE
menu.

Peak wavelength

Center wavelength

Threshold
(20 dB)

Setting the measurement range to the waveform display zoom range (View Scale ->
Measure)

The measurement range values (center value, sweep span, start point, stop point) are set to
the zoom range values (Zoom Center, Zoom Span, Zoom Start, Zoom Stop) on the ZOOM
menu.

1-10

IM AQ6380-01EN

1.1 Measuring the Optical Spectrum

SPAN key

“Measurement range” in Features

Sweep span (Span)

The sweep span to be measured. The specified value is displayed in the measurement
conditions area. The unit of values (wavelength or frequency) is set using Horizontal Scale on
the SETUP menu.

Start wavelength and start frequency (Start)

This is the start point of the measurement range. The specified value is displayed in the
measurement conditions area. The unit of values (wavelength or frequency) is set using
Horizontal Scale on the SETUP menu.

Stop wavelength and stop frequency (Stop)

This is the stop point of the measurement range. The specified value is displayed in the
measurement conditions area. The unit of values (wavelength or frequency) is set using
Horizontal Scale on the SETUP menu.

Note

• If you change the measurement range start point (Start) or measurement range stop point (Stop),
the measurement range center (Center) and sweep span (Span) will change.

• If you change the measurement range center (Center), the sweep span (Span) will not change.

1

Features

Setting the sweep span to the spectral width (Δλ -> Span)

The instrument analyzes the spectral width of the waveform of the trace (A to G) selected
using Active Trace on the TRACE menu and sets the sweep span to the obtained result. The
spectral width is analyzed by the RMS method (threshold value = 20 dB), and a value six
times the obtained spectral width is assigned to the the sweep span.

Threshold
20 dB

Optical power

Wavelength

For the calculation
formula, see appendix 2.

Level fluctuation measurement time (0nm Sweep Time)

Set the time required to measure from the left edge to the right edge of the screen when the
sweep span is 0 nm. When the sweep span is set to 0 nm, the center, start point, and end
point of the measurement range will be of the same wavelength. The instrument will measure
the level fluctuations of a single wavelength. When level fluctuations are measured, the
horizontal scale unit is time. The time set on this menu becomes the range from the left edge
to the right edge of the waveform display area.

IM AQ6380-01EN

Setting the measurement range to the waveform display zoom range (View Scale ->
Measure)

The measurement range values (center value, sweep span, start point, stop point) are set to
the zoom range values (Zoom Center, Zoom Span, Zoom Start, Zoom Stop) on the ZOOM
menu.

1-11

1.1 Measuring the Optical Spectrum

LEVEL key

Main scale settings

• Reference level (Reference Level)

The level value that determines where to display the spectral waveform.
In log scale display, the spectral waveform is displayed so that the position at the vertical
scale setting (Y Scale Setting) matches the reference level value.
In linear scale display, the spectral waveform is displayed so that the reference level is
positioned at the top of the screen.

• Log scale display (Log Scale) and linear scale display (Linear Scale)

The vertical scale unit can be switched between log scale display (Log Scale) and linear
scale display (Linear Scale). The log scale display shows the scale with the linear value of
1 mW assigned to the log value of 0 dBm.
For example, if the level range of the measured waveform in terms of log values is –80 dBm
to +10 dBm and these values are displayed with linear values, they will be –10 pW to
10 mW. Since the level range of spectral waveform is very wide, in the case of a spectral
waveform with peaks and subpeaks such as a DFB-LD light source, using a logarithmic
scale makes it possible to display both peaks in the waveform display area.

“Level scale” in Features

• Bottom of the linear scale (Linear Base Level)

This is the level value at the bottom of the spectral waveform displayed in the waveform
display area during linear scale display. When set to 0, the entire spectral waveform is
displayed in the waveform display area. When set to a value close to the peak level value,
the vertical axis can be expanded to display the spectral waveform.

• Setting the reference level to the peak level (Peak Level -> Ref Level)

The reference level is set to the peak level of the active trace waveform. The specified
reference level (peak level value) and waveform are displayed in a reference level setting
window. Then, you can further change the reference level.

• Auto setting of the reference level (Auto Ref Level)

Each time a measurement is completed, the peak level of the spectral waveform is
automatically detected, and this value is used as the reference level to display the spectral
waveform in the waveform display area.

• Switching the power spectral density display (Level Unit)

dBm and W are units of level (power value) per resolution step.
dBm/nm and W/nm are units converted to the level per 1 nm wavelength width (power
spectral density). When measuring a light source with a spectrum that is wider than the
measurement resolution, such as an LED or ASE light source, displaying the spectral
waveform in units of power spectral density reduces the change in the measurement
spectrum due to the difference in resolution.

1-12

• Initializing the main scale display (Main Scale Initialize)

If the main scale is expanded or reduced after measurement, initialization returns the main
scale to its original setting.

IM AQ6380-01EN

1.1 Measuring the Optical Spectrum

Sub scale settings

Calculated values are displayed using a sub scale when a trace-to-trace calculation waveform,
such as trace C, trace F, and trace G, is displayed.

• Log sub scale display (Sub Log)

When calculated waveforms (see sections 4.5 and 4.6) are displayed, the calculation result
is displayed on a log scale. The scale of the calculation results is displayed on the right or
left side of the waveform display area.

• Linear sub scale display (Sub Linear)

When calculated waveforms (see sections 4.5 and 4.6) are displayed, the calculation result
is displayed on a linear scale. The scale of the calculation results is displayed on the right
or left side of the waveform display area.

• Percentage sub scale display (Sub Scale)

When calculated waveforms (see sections 4.5 and 4.6) are displayed, the calculation result
is displayed on a percentage scale. The scale of the calculation results is displayed on the
right or left side of the waveform display area.

• Applying an offset to the log sub scale (Offset Level)

The display position of a calculated waveform can be moved from its original position by
applying an offset to the log value of the calculation result displayed on a log sub scale.
This is possible when the log sub scale is displayed.

1

Features

• Lower limit of the linear sub scale (Scale Minimum)

The display position of a calculated waveform can be moved from its original position by
changing the display range of the linear value of the calculation result displayed on a linear
sub scale. The entire calculated waveform range can be displayed by specifying zero. This
is possible when the linear sub scale is displayed.

• Auto setting of the sub scale (Auto Sub Scale)

When trace-to-trace calculation is executed in a calculated waveform display (see section

4.5), the above sub scale items (Sub Log, Sub Linear, Sub Scale, Offset Level, Scale

Minimum) are automatically set, and the calculated waveform is displayed at the optimum
position in the waveform display area.

• Initializing the sub scale display (Main Scale Initialize)

If the sub scale is expanded or reduced after measurement, initialization returns the scale
to its original setting.

Vertical scale setting (Y Scale Setting)

Number of divisions in the vertical scale (Y Scale Division)

Set the number of divisions in the vertical scale.

Position to display the reference value of the main scale (Ref Level Position)

Set the number of divisions from the bottom of the waveform display area at which the
main scale reference value will be displayed.

IM AQ6380-01EN

Position to display the reference value of the log sub scale (Sub Ref Level Position)

Set the number of divisions from the bottom of the waveform display area at which the sub
scale reference value (0.0 dB) will be displayed.

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1.1 Measuring the Optical Spectrum

SETUP key

“Measurement range,” “Wavelength resolution,” “Measurement sensitivity,”

Wavelength resolution (Resolution)

Set the wavelength resolution for measuring spectra. Select from the available values, or enter
a value of your choice (Custom).

Measurement sensitivity (Sensitivity)

Measurement sensitivity mode (Sensitivity Mode)

This instrument has two measurement sensitivity modes: RAPID and TRAD. You can set
the mode with Sensitivity Mode. Setting this mode sets the operation mode of the analog
amplifier circuit (internal amplifier) built into the instrument.

RAPID: Sensitivity mode specialized for high-speed measurement of CW light
TRAD: Conventional sensitivity mode for CW light and pulse light measurements

Measurement sensitivity selection (Sensitivity Select)

Select the measurement sensitivity from the menu.

RAPID

Low

Sensitivity

High

TRAD

Low

Sensitivity

High

“Averaged measurement,” “Roll-averaged measurement,”

“Sampling points and sampling interval,” in Features

Menu

RAPID1
RAPID2
RAPID3
RAPID4
RAPID5
RAPID6

Menu

N/HOLD

N/AUTO(x2)

N/AUTO

NORMAL(x2)

NORMAL

MID(x2)

MID

HIGH1(x2)

HIGH1

HIGH2(x2)

HIGH2

HIGH3(x2)

HIGH3

Fast

Sweep speed

Slow

Fast

Sweep speed

• The internal amplifier is set to fixed
gain for N/HOLD. Otherwise, the
internal amplifier is set to auto gain.

• (x2) indicates double speed mode.

Slow

1-14

Manual setting of the measurement sensitivity (Sensitivity Level)

Enter the approximate lowest level of the waveform you want to measure as a numerical
value (dBm), and the measurement sensitivity will be automatically selected according to
that value.

Using the CHOP mode (Chop Mode)

When the CHOP mode is set to SWITCH, measurements are made while reducing the
stray light in the monochromator (spectrometer), which is generated according to the
intensity of the input light power. The measurement time is doubled, but a wide dynamic
range can be measured. For details on monochromator stray light, see section 3.1.

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1.1 Measuring the Optical Spectrum

Average times (Average Times)

The signal-to-noise ratio (S/N ratio) of measured spectra is improved by carrying out
measurements several times and averaging the measurement results. Measurements using
average times is possible when the measurement sensitivity mode is set to standard (TRAD)
and a setting that does not have (x2) displayed in the measurement sensitivity menu (sweep
speed twice the normal speed) is selected.

Number of samples (Sampling Points)

Number of samples (sampling points) is the number of points measured within the range
of the specified sweep span. When you set the sampling points, the sampling interval is
automatically determined. A smaller number of samples will result in shorter measurement
times but a wider sampling interval. Measurement spectra will be inaccurate if the number of
samples is too small. The recommended sampling interval setting varies depending on the
resolution as shown below. If the specified number is less than the sampling points indicated
here, the letters “UNCAL” will appear in the waveform display area to indicate that the
measurement conditions are inappropriate. In normal cases, set the sampling points to AUTO.

• About SMPL AUTO (sampling interval conditions that do not cause UNCAL)

In this instrument, sampling intervals that do not cause UNCAL differ depending on the set
resolution as shown below.
For example, to prevent UNCAL from occurring at a resolution setting of 0.05 nm, the
sampling interval must be 0.002 nm or less. In this case, to measure a 20 nm span, the
sample points must be set at least to 20 ÷ 0.002 + 1 = 10001.

1

Features

Measurement resolution settings and sampling intervals that do not cause UNCAL

Resolution setting Sampling interval that does

0.005 nm 0.001 or less

0.01 nm 0.001 or less

0.02 nm 0.002 or less

0.05 nm 0.002 or less

0.1 nm 0.01 or less

0.2 nm 0.01 or less

0.5 nm 0.01 or less
1 nm 0.01 or less
2 nm 0.01 or less

not cause UNCAL [nm]

Sampling interval (Sampling Interval)

Sampling interval is the wavelength spacing at which measured data sampled. It is
automatically determined when you set the sweep span and sampling points. If you set a wide
sampling interval within the set sweep span range, the number of samples will automatically
decrease.
The sampling interval can be determined with the following formula.

sampling interval = sweep span (SPAN) ÷ (sampling points – 1)

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1.1 Measuring the Optical Spectrum

Pulse light measurement mode (Pulse Light Measure)

Set the measurement mode for measuring pulse light.
For details on each mode, see section 3.3.

• Peak hold mode (Peak Hold)

Set the peak hold value of the pulse light. The pulse light is measured based on this value.

• External trigger mode (Ext Trigger Mode)

A mode in which measurements are made by synchronizing the pulse light to the external
trigger signal. Set the trigger conditions in the Trigger Setting menu.

Gate mode (Gate Mode)

The instrument samples data when the external signal (gate signal) is active and measures
the pulse light. The instrument receives the gate signal synchronized with the timing at which
pulse light is emitted. In the Gate Setting menu, you need to set the gate mode sampling
interval and signal logic.

Gate mode setting (Gate Setting)

• Gate sampling interval (Gate Sampling Interval)

Set the sampling interval (average duration per sampling point).

• Signal logic (Gate Logic) for displaying pulse light based on gate signals

This is the signal logic with which the gate signal is enabled.

• Measurement delay (Measure Delay)

Sets the time required for the pulse light emission to stabilize.
Data is not measured until the measurement delay has elapsed after the gate signal is
input.

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1.1 Measuring the Optical Spectrum

External trigger setting (Trigger Setting)

Edge (Edge)

You can set the external trigger signal’s edge detection type to rising or falling.

Delay (Delay)

This is the delay time from the edge detection of the trigger signal to the start of waveform
sampling.

Trigger operation type (Trig Input Mode)

• Sampling trigger (Smpl Trig Mode)
Waveforms are sampled with the rising or falling edge of the external signal as a trigger.

• Sweep start trigger (Sweep Trig Mode)
The instrument sweeps with the rising edge of the external signal as a trigger.

• Sweep enable/disable control (Smpl Enable Mode)
When the external signal level is low (Low), the instrument sweeps (Single/Repeat).
When the external signal level changes to high (High), sweeping is paused.
When the external signal level changes to low again, sweeping resumes from the
paused position.

Trigger signal output (Trig Output Mode)

• Sweep status signal output (Sweep Status)
The instrument outputs a positive logic (high) signal when sweeping is in progress and
a negative logic (low) signal when sweeping is not in progress from the instrument’s
TRIGGER OUT (trigger output) terminal.

1

Features

Horizontal scale unit (Horizontal Scale)

Select the horizontal scale unit of the waveform display area. The unit switches between nm
and THz each time you press Horizontal Scale.

Noise rejection (Smoothing)

This function reduces the noise in the measurement waveform. Waveform areas where noise
is superimposed can be smoothed and measured. Note that when noise is superimposed
on sudden changes in the spectrum, the wavelength resolution of the peaks or valleys of the
spectrum may be reduced due to the effects of averaging.

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1.1 Measuring the Optical Spectrum

RESOLN key

Wavelength resolution (Resolution)

Set the wavelength resolution for measuring spectra. Select from the available values, or enter
a value of your choice (Custom).

SWEEP key

Auto sweep (Auto)

This function automatically sets the center wavelength (Center), sweep span (Span),
reference level (Reference Level), and resolution (Resolution) and measures the spectrum.
When an auto configuration of measurement conditions is completed in an auto sweep, the
sweep mode changes to repeat sweep.

Repeat sweep (Repeat)

This function repeatedly sweeps the specified measurement wavelength (frequency) range
and measures the spectrum.

“Wavelength resolution,” in Features

“Starting a measurement (sweep),” in Features

Single sweep (Single)

This function sweeps the specified measurement wavelength (frequency) once and measures
the spectrum.

Measurement stop (Stop)

Stops sweeping.

Inter-line marker sweep (Sweep Marker L1-L2)

This function sweeps the range between line markers L1 and L2 and measures the spectrum.

Sweep interval (Sweep Interval)

This function is used to set the time from the start of one sweep to the start of the next sweep.

SENS key

“Measurement sensitivity,” in Features

Measurement sensitivity selection (Sensitivity Select)

Select the measurement sensitivity from the menu.

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1.2 Displaying Optical Spectral Waveforms

Traces

Traces A to G can be displayed simultaneously in the instrument’s waveform display area. In
addition to displaying measured waveforms, traces C, F, and G can be used to execute trace
calculations and display waveforms of the calculation results.

Calculation result trace

1

Features

Trace

Optical power

Calculation
result trace

NORMALIZE, CURVE FIT, PEAK CURVE FIT

A, B, C

LOG calculation

C-F, F-C, C+F, E-F, F-E, E+F

Linear calculation

C+F, C-F, F-C, E+F, E-F, F-E

MARKER FIT

Calculation
result trace

POWER/NBW

A, B, C, D, E

LOG calculation

C-D, D-C, C+D, D-E, E-D, D+E

Linear calculation

C+D, C-D, D-C, D+E, D-E, E-D

A B CDE F

Trace G

Trace F

G

Wavelength

Trace A

Trace B

Trace E

Trace A

Trace B

Trace D

Trace E

Calculation
source trace

IM AQ6380-01EN

Calculation
result trace

Trace C

LOG calculation

A+B, A-B, B-A

Linear calculation

A+B, A-B, B-A, 1-k(A/B), 1-k(B/A)

Trace A

Trace B

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FUNCTION

1.2 Displaying Optical Spectral Waveforms

REPEAT SINGLE

AUTO

STOP

CENTER

SWEEP

SETUP

MARKER

USER

REMOTE

UNDO/
LOCAL

RESOLN

ZOOM

SEARCH

SYSTEM

HELP

SPAN

PEAK

PRT
SCN

LEVEL

SENS

TRACE

ANALYSIS

FILE

APP

PRESET

TRACE

Write, fix, hold, rolling average, calculate

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1.2 Displaying Optical Spectral Waveforms

Zoom

The waveform display area can be zoomed by specifying the display range of the measured
spectral waveform.
How to set the zoom range

• Combination of the zoom center value (Zoom Center) and display span (Zoom Span)

• Combination of the zoom start point (Zoom Start) and stop point (Zoom Stop)

Zoom center value

Zoom start point Zoom stop point

Optical power

Wavelength

Zoom display span

Zoomed waveform display

Optical power

Wavelength

1

Features

AUTO

CENTER

SWEEP

SETUP

MARKER

USER

REMOTE

UNDO/

LOCAL

FUNCTION

REPEAT SINGLE

SPAN

RESOLN

ZOOM

PEAK

SEARCH

SYSTEM

PRT

HELP

SCN

STOP

LEVEL

SENS

TRACE

ANALYSIS

FILE

APP

PRESET

ZOOM

Zoom center value, Zoom display span,
zoom start point, zoom stop point

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1-21

Wavelength

Optical power

Moving marker

FUNCTION

1.2 Displaying Optical Spectral Waveforms

Peak search

This function determines the peak (local maximum value) and the bottom (local minimum value) of
the active trace waveform and sets the moving marker. Based on the set moving marker, you can
search for the next peak or bottom and search for the peak or bottom on the right or left side of the
moving marker.
By placing a fixed marker at the moving marker position, you can view the wavelength difference
and power difference between a fixed marker and the moving marker.

Peak search

Searches for the next peak

0001

or the adjacent peak on the
right of the peak value
Fixed marker

REPEAT SINGLE

AUTO

CENTER

SWEEP

SETUP

MARKER

USER

UNDO/
LOCAL

REMOTE

HELP

SPAN

RESOLN

ZOOM

PEAK

SEARCH

SYSTEM

PRT
SCN

STOP

LEVEL

SENS

TRACE

ANALYSIS

FILE

APP

PRESET

PEAK SEARCH

Peak search, bottom search, level
order search, left and right search,
fixed marker placement

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IM AQ6380-01EN

Optical power

Normal marker

Power spectral density marker

Optical power

Integral range

1.2 Displaying Optical Spectral Waveforms

Markers

You can set markers on the active trace waveform to display in the data area the wavelengths or
frequencies and power values at the market positions. There are three types of markers based on
the power value calculation methods.

Power value calculation based on marker type

• Normal marker

Power values are determined at the marker positions on the waveform.

• Power spectral density markers

The power values per specified normalization bandwidth are determined by assuming the marker
position on the waveform to be the center. These markers are used to determine converted
power values per given bandwidth such as when measuring the signal noise level.

• Integral markers

The integrated power values over specified frequency ranges are displayed by assuming the
marker position on the waveform to be the center. The power values are displayed in the data
area. These markers are used to determine the integrated power of a widely spread spectrum
such as to determine the signal level from a modulated optical signal spectrum.

1

Features

Moving marker

Integral marker

Moving marker

Power value of
the wavelength
at the marker
position

Wavelength

Center value of
the integration
range

Moving marker

Optical power

Bandwidth power density

Wavelength

Normalization
bandwidth

Integral
power value

IM AQ6380-01EN

Wavelength

1-23

FUNCTION

1.2 Displaying Optical Spectral Waveforms

REPEAT SINGLE

AUTO

STOP

CENTER

SWEEP

SETUP

MARKER

USER

REMOTE

UNDO/
LOCAL

RESOLN

ZOOM

SEARCH

SYSTEM

HELP

SPAN

PEAK

PRT
SCN

LEVEL

SENS

TRACE

ANALYSIS

FILE

APP

PRESET

MARKER->Marker Setting

Normal marker, power spectral
density marker, integral marker

1-24

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1.2 Displaying Optical Spectral Waveforms

Function menus

TRACE key

“Traces” in Features

Active trace (Active Trace)

An active trace is a trace in a state that allows it to be set, changed, analyzed, and so on. For
example, one-action setup such as Peak WL -> Center, moving marker operation, waveform
searching, and various analysis are performed on the active trace.
Select the active trace from A to G.

Showing and hiding (View A to G)

The spectral waveforms drawn in traces A to G are displayed in the waveform display area.

Write mode (Write A to G)

The spectral waveform is drawn in the active trace, and the waveform in the trace is updated
and displayed in the waveform display area.

Fixed mode (Fix A to G)

The spectral waveform is not drawn in the active trace. The waveform in the trace is not
updated, and the waveform drawn immediately before is displayed in the waveform display
area.

1

Features

Hold mode (Hold A to G)

The selected spectral waveform, either the spectral waveform with the maximum peak or that
with the minimum peak, is drawn in the active trace to update the waveform in the trace and
displayed in the waveform display area. Since only spectral waveforms with the maximum
peak or those with the minimum peak are drawn in the active trace, the spectral waveforms
with the maximum peak or those with the minimum peak are held and the waveform display
area.

Rolling average mode (Roll Average A to G)

The spectral waveform drawn in the trace immediately before and the newly measured
spectral waveform are averaged the specified number of times, and the result is displayed in
the waveform display area. For example, if 10 is specified, waveforms are swept 10 times, and
then the averaged spectral waveform in the waveform display area is updated.
Averaging is performed using the following formula.
Wj(i) = Wj–1(i)•(n – 1)/n + W(i)•1/n (i=1, 2, ..., N)

Wj (i): newly displayed waveform
Wj-1(i): previously displayed waveform
W (i): newly obtained waveform
N: number of samples
n: average times

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1.2 Displaying Optical Spectral Waveforms

Calculation mode (Calculate C, F, G)

The result of the selected calculation is displayed in the waveform display area.

Trace C (Calculate C)

• Log Math

This function performs LOG calculations on trace-to-trace data and write the results to
trace C.
Calculations can be applied to trace A and trace B.

C=A-B(LOG) Subtracts trace B from trace A in LOG form.
C=B-A(LOG) Subtracts trace A from trace B in LOG form.
C=A+B(LOG) Adds trace A and trace B in LOG form.

• Linear Math

This function performs linear calculations on trace-to-trace data and write the results to
trace C.
Calculations can be applied to trace A and trace B.

C=A+B(LIN) Adds trace A and trace B in linear form.
C=A-B(LIN) Subtracts trace B from trace A in linear form.
C=B-A(LIN) Subtracts trace A from trace B in linear form.
C=1-k(A/B) Given trace A and trace B, calculates 1-k(A/B).

Calculates 1-k × (trace A/Trace B) (linear value), and writes the results to

trace C.

The coefficient k can be changed in the range of 1.0000 to 20000.0000

(in steps of 0.0001). If COARSE is enabled in the setting window, you can
change the value in 1-2-5 steps.

The coefficient k setting applies to both the <C=1-k(A/B)> calculation and

<C=1-k(B/A)> calculation.
The display in the trace area changes to 1-k(A/B).
C=1-k(B/A) Given trace A and trace B, calculates 1-k(B/A).
Calculates 1-k × (trace B/Trace A) (linear value), and writes the results to

trace C.
The display in the trace area changes to 1-k(B/A).

1-26

The calculation results of C=A+B(LIN), C=A-B(LIN), and C=B-A(LIN) are displayed
using the main scale.
The calculation results of C=1-k(A/B) and C=1-k(B/A) are displayed using the sub scale.
For details on sub scales, see section 2.6.

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1.2 Displaying Optical Spectral Waveforms

Trace F (Calculate F)

• Log Math

This function performs LOG calculations on trace-to-trace data and write the results to
trace F.
Calculations can be applied to trace C, trace D, and trace E.

F=C-D(LOG) Subtracts trace D from trace C in LOG form.
F=D-C(LOG) Subtracts trace C from trace D in LOG form.
F=C+D(LOG) Adds trace C and trace D in LOG form.
F=D-E(LOG) Subtracts trace E from trace D in LOG form.
F=E-D(LOG) Subtracts trace D from trace E in LOG form.
F=D+E(LOG) Adds trace D and trace E in LOG form.

The calculation results are displayed using the sub scale. The scale for the calculation
results is displayed on the left or right side of the screen. For details on sub scales, see
section 2.6.

• Linear Math

This function performs linear calculations on trace-to-trace data and write the results to
trace F.
Calculations can be applied to trace C, trace D, and trace E.

1

Features

F=C+D(LIN) Adds trace C and trace D in linear form.
F=C-D(LIN) Subtracts trace D from trace C in linear form.
F=D-C(LIN) Subtracts trace C from trace D in linear form.
F=D+E(LIN) Adds trace D and trace E in linear form.
F=D-E(LIN) Subtracts trace E from trace D in linear form.
F=E-D(LIN) Subtracts trace D from trace E in linear form.

The calculation results are displayed using the main scale.

• Power/NBW

Displays in trace F the power per the specified band in the range of 0.1 nm to 10 nm in

0.1 nm resolution. The applicable calculation traces are A to E.

F=Pwr/NBW A Displays the power spectral density of trace A.
F=Pwr/NBW B Displays the power spectral density of trace B.
F=Pwr/NBW C Displays the power spectral density of trace C.
F=Pwr/NBW D Displays the power spectral density of trace D.
F=Pwr/NBW E Displays the power spectral density of trace E.
Bandwidth Sets the bandwidth.

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1.2 Displaying Optical Spectral Waveforms

Trace G (Calculate G)

• Log Math

This function performs LOG calculations on trace-to-trace data and write the results to
trace G.
Calculations can be applied to trace C, trace E, and trace F.

G=C-F(LOG) Subtracts trace F from trace C in LOG form.
G=F-C(LOG) Subtracts trace C from trace F in LOG form.
G=C+F(LOG) Adds trace C and trace F in LOG form.
G=E-F(LOG) Subtracts trace F from trace E in LOG form.
G=F-E(LOG) Subtracts trace E from trace F in LOG form.
G=E+F(LOG) Adds trace E and trace F in LOG form.

The calculation results are displayed using the sub scale. The scale for the calculation
results is displayed on the left or right side of the screen. For details on sub scales, see
section 2.6.

• Linear Math

This function performs linear calculations on trace-to-trace data and write the results to
trace G.
Calculations can be applied to trace C, trace E, and trace F.

G=C+F(LIN) Adds trace C and trace F in linear form.
G=C-F(LIN) Subtracts trace F from trace C in linear form.
G=F-C(LIN) Subtracts trace C from trace F in linear form.
G=E+F(LIN) Adds trace E and trace F in linear form.
G=E-F(LIN) Subtracts trace F from trace E in linear form.
G=F-E(LIN) Subtracts trace E from trace F in linear form.

The calculation results are displayed using the main scale.

• Normalize

This is one of the calculations that normalizes trace data. This function writes
the normalize result in trace G and displays it. One of the following traces can be
normalized: trace A, trace B, or trace C. The peak of the normalized waveform is 1 if
trace G is set to linear scale or 0 dB if it is set to LOG scale. Data is displayed when
sweeping is finished to the end.
The trace area display changes to NORM @.

G=NORM A Normalizes trace A and writes the normalized data to trace G.
G=NORM B Normalizes trace B and writes the normalized data to trace G.
G=NORM C Normalizes trace C and writes the normalized data to trace G.

The calculation results are displayed using the sub scale. The scale for the calculation
results is displayed on the left or right side of the screen. For details on sub scales, see
section 2.6.

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1.2 Displaying Optical Spectral Waveforms

• Curve Fit

Curve fitting is applied to the specified trace waveform, and the results are drawn in
trace G. Calculations are performed on data from the threshold to the peak.

G=CRV FIT A Applies curve fitting to trace A.
G=CRV FIT B Applies curve fitting to trace B.
G=CRV FIT C Applies curve fitting to trace C.
G=MKR FIT Applies curve fitting to the placed markers using the current

measurement scale. Curve fitting is applied even when markers
are placed on different traces.

Threshold Set the threshold value.
Operation Area Set the calculation target range.
ALL Includes all data in the calculation target trace in the

calculation.

INSIDE L1-L2 Includes the data between the line markers in the calculation.
OUTSIDE L1-L2 Includes the data outside the line markers in the calculation.
Fitting Algorithm Select the curve fitting formula.
GAUSS Normal distribution curve
LORENZ Lorenz curve
3RD POLY 3rd order polynomial
4TH POLY 4th order polynomial
5TH POLY 5th order polynomial

1

Features

• Peak Curve Fit

Peak curve fitting is applied to the specified trace waveform, and the results are drawn
in trace G. Calculations are performed on mode peaks that are greater than or equal to
the threshold.

G=PKCV FIT A Applies peak curve fitting to trace A.
G=PKCV FIT B Applies peak curve fitting to trace B.
G=PKCV FIT C Applies peak curve fitting to trace C.
Threshold Set the threshold value.
Operation Area Set the calculation target range.
Fitting Algorithm Select the curve fitting formula.
GAUSS Normal distribution curve
LORENZ Lorenz curve
3RD POLY 3rd order polynomial
4TH POLY 4th order polynomial
5TH POLY 5th order polynomial

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1.2 Displaying Optical Spectral Waveforms

Trace list (Trace List)

Lists the measurement conditions and display conditions of all traces.

Inter-trace waveform copy (Trace Copy)

Copies waveforms between traces.

Trace clear (Trace Clear)

Clears the waveforms in the trace.

Label (Label)

Enter the character string to display in the label area of the screen.

Noise mask (Noise Mask)

Masks the display of spectral waveforms whose level is less than the specified level.

Mask line (Mask Line)

When mask line is set to VERT, the waveform is displayed with level values at or below

the specified mask value as the display lower limit value (−210 dBm).

When mask line is set to HRZN, the waveform is displayed with level values at or below
the specified mask value as the mask value.

Trace highlighting (Trace Highlight)

Highlights the waveform of the selected trace.

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1.2 Displaying Optical Spectral Waveforms

ZOOM key

“Zoom” in Features

How to set the zoom range

• Combination of the zoom center value (Zoom Center) and display span (Zoom Span)

• Combination of the zoom start point (Zoom Start) and stop point (Zoom Stop)

Zoom center wavelength or frequency (Zoom Center)

This is the center value of the zoom range.

Zoom display span (Zoom Span)

This is the display span of the zoom range. The spectral waveform is displayed with the zoom
center wavelength at the center and at the specified zoom display span.

Start wavelength and start frequency (Zoom Start)

This is the start point of the zoom range. The specified value is displayed at the left end of the
waveform display area.
The horizontal scale unit is set using Horizontal Scale on the SETUP menu.

Stop wavelength and stop frequency (Zoom Stop)

This is the stop point of the Zoom range. The specified value is displayed at the right end of
the waveform display area.
The horizontal scale unit is set using Horizontal Scale on the SETUP menu.

1

Features

Note

• If you change the zoom start point (Zoom Start) or stop point (Zoom Stop), the zoom center value
(Zoom Center) and sweep span (Zoom Span) will change.

• If you change the zoom center value (Zoom Center), the sweep span (Zoom Span) will not change.

Setting the center of the zoom range to the peak wavelength of the waveform (Peak ->
Zoom Ctr)

The center of the zoom range is set to the peak wavelength of the trace (A to G) selected
using Active Trace on the TRACE menu.

Overview window display (Overview Display)

When a spectral waveform is displayed zoomed, an overview window can be displayed. In the
overview window, you can check which part of the spectral waveform is displayed zoomed.

Setting the measurement range to the waveform display zoom range (View Scale ->
Measure)

The measurement range values (center value, sweep span, start point, stop point) are set to
the zoom range values (Zoom Center, Zoom Span, Zoom Start, Zoom Stop) on the ZOOM
menu.

Zoom range initialization (Initialize)

Initializes the zoom range values (Zoom Center, Zoom Span, Zoom Start, Zoom Stop).

IM AQ6380-01EN

1-31

Data area

Δ0001 to Δ1024: fixed markers

1.2 Displaying Optical Spectral Waveforms

PEAK SEARCH key

Peak search (Peak Search)

A peak search (a search for the maximum level value) is performed on the active trace
waveform.
The moving marker is displayed at the peak point, and the marker value is displayed in the
data area.

Bottom search (Bottom Search)

A bottom search (a search for the minimum level value) is performed on the active trace
waveform.
The moving marker is displayed at the bottom point, and the marker value is displayed in the
data area.

Next level search (Next Level Search)

On the active trace waveform, the moving marker at the peak or bottom is moved to the next
peak (local maximum value) or bottom (local minimum value).

Next search right (Next Search Right)

On the active trace waveform, the moving marker at the peak or bottom is moved to the peak
(local maximum value) or bottom (local minimum value) on its right.

“Peak search” in Features

Next search left (Next Search Left)

On the active trace waveform, the moving marker at the peak or bottom is moved to the peak
(local maximum value) or bottom (local minimum value) on its left.

Fixed marker placement (Set Marker)

Places a fixed marker with the assigned number at the moving marker position.

Δ: moving marker
ΔPK: peak moving marker
ΔBT: bottom moving marker

Difference between
markers

Fixed marker clear (Clear Marker)

Clears the specified fixed marker number. The marker value in the data area is also cleared.

Clearing all markers (All Marker Clear)

Clears all moving markers and fixed markers.

1-32

Auto search (Auto Search)

Turns on or off peak/bottom searching that is performed every sweep.
When set to On, after sweeping ends, a peak/bottom search is performed automatically, and a
moving marker is set automatically.

IM AQ6380-01EN

1.2 Displaying Optical Spectral Waveforms

Spectral waveform mode threshold (Mode Diff)

Sets the minimum peak/bottom difference (dB) serving as a basis for mode determination
during mode detection.

Search between wavelength line markers (L1 and L2) (Search/Ana Marker L1-L2)

If you set Search/Ana Marker L1-L2 to On when wavelength line markers L1 and L2 are on,
the peak/bottom search target is set between line markers 1 and 2.

Search in the waveform display zoom range (Search/Ana Zoom Area)

When Search/Ana Zoom Area is set to On, the peak/bottom search is performed on the data
in the zoom display range. If Search/Ana and Zoom Area Search/Ana Marker L1-L2 are both
set to On, search is performed in the area where the zoom display range and line marker
range overlap.

Search mode (Search Mode)

The peak search function described earlier is a “single search” function that executes searches
one by one. When the search mode is set to “multi search,” the peak (maximum power value)
and bottom (minimum power value) of all spectral waveforms that meet the search conditions
are searched in a single search.

1

Features

Multi search conditions (Multi Search Setting)

Threshold (Threshold)

Set the threshold (detection range level) that is used when the multi search detects modes
(peaks/bottoms). For peak searches, the peak detection range is defined as being the
levels from the measured waveform's maximum peak to the threshold value. For bottom
searches, the bottom detection range is defined as being the levels from the measured
waveform's minimum bottom to the threshold value.

Sorting the data area display (Sort by)

Set the assignment order of marker numbers. The detected marker values are displayed
as a list in the data area. This setting sets the sort order of the detection list.

IM AQ6380-01EN

1-33

1.2 Displaying Optical Spectral Waveforms

MARKER key

Moving marker display (Marker Active)

You can move the moving marker to any wavelength using the rotary knob, arrow keys, or
numeric keypad. You can also drag it with the mouse. The moving marker moves along the
waveform, and the marker values are displayed in the data area. If you fix the moving marker
at a given position, it turns into a fixed marker. The moving marker applies to the active trace.

Fixed marker display (Set Marker)

A marker fixed to a specific number using the moving marker is called a fixed marker. You can
place up to 1024 fixed markers. Fixed markers can be placed across different traces.
Fixed markers are assigned marker numbers in order from 0001.

Fixed marker clear (Clear Marker)

Clears the fixed marker with the selected number.

Marker selection (Marker Setting)

Select a marker you want to use from the three available markers: normal, power spectral
density, and integral.

“Markers” in Features

Normalization bandwidth (Band Width)

Set the normalization bandwidth of the power spectral density marker.

Setting the center of the measurement range to the wavelength of the moving marker
position (Marker -> Center)

The center of the zoom range is set to the wavelength of the moving marker position in the
waveform of the trace (A to G) selected using Active Trace on the TRACE menu.

Setting the center of the zoom range to the wavelength of the moving marker position
(Peak -> Zoom Ctr)

The center of the zoom range is set to the wavelength of the moving marker position in the
waveform of the trace (A to G) selected using Active Trace on the TRACE menu.

Setting the reference level to the level of the moving marker position (Marker -> Ref
Level)

The spectral waveform is displayed in the waveform display area by assuming the level value
at a moving marker position to be the reference level in the waveform of the trace (A to G)
selected using Active Trace on the TRACE menu.

Clearing all markers (All Marker Clear)

Clears all displayed fixed markers and moving markers.

1-34

Wavelength line markers (Line Marker 1, 2)

Wavelengths are displayed as position information in the waveform display area. If two
line markers are displayed, the difference in wavelengths between the line markers can be
displayed. In addition, two line markers can be displayed and used to set the sweep span,
zoom range, and resolution range.

IM AQ6380-01EN

1.2 Displaying Optical Spectral Waveforms

Level line markers (Line Marker 3, 4)

Level values are displayed as position information in the waveform display area. If two
line markers are displayed, the difference in level values between the line markers can be
displayed.

Setting the sweep span to the range between the wavelength line markers (Marker L1­L2 -> Span)

The sweep span is set to the wavelength range between the wavelength line markers.

Setting the zoom range to the spacing between the wavelength line markers (Marker L1­L2 -> Zoom Span)

The zoom range is set to the wavelength range between the wavelength line markers.

Clearing all line markers (Marker All Clear)

Clears all displayed line markers (L1 to L4).

Marker difference information display method (Marker Display)

This function sets whether to display the difference relative to the moving marker (Offset) or
the difference relative to the next marker (Spacing) in the marker display.

Auto updating the marker information (Marker Auto Update)

When a sweep is made and the measurement spectral data is updated, the placement of fixed
markers is updated automatically, and the marker information of the new spectral waveform is
displayed.

1

Features

Unit for displaying marker information (Marker Unit)

Set the unit (wavelength or frequency) of the marker information displayed in the data area.

Search or analysis between wavelength line markers (L1 and L2) (Search/Ana Marker
L1-L2)

Peak search, bottom search, and calculation of analysis function (ANALYSIS key) can be
performed in the area between wavelength line markers L1 and L2. Set the wavelength line
markers using Line Marker 1 and Line Marker 2 in the MARKER menu.

Search and analysis in the waveform display zoom range (Search/Ana Zoom Area)

Peak search, bottom search, and calculation of analysis function (ANALYSIS key) can be
performed in the zoom range of the waveform display. Set the zoom range using Zoom
Center, Zoom Span, Zoom Start, and Zoom Stop in the ZOOM menu.

Sweeping between wavelength line markers (Sweep Marker L1-L2)

The instrument sweeps the wavelength range between the wavelength line markers.

IM AQ6380-01EN

1-35

1.3 Analyzing the Optical Spectrum

Optical power

THRESH method

NOTCH width search

Optical power

Wavelength

FUNCTION

Spectral width

This function calculates the spectral width of the active trace waveform. Select the analysis
algorithm from the following four types.

Threshold (3 dB)

Spectral width (Δλ)

Wavelength

Center wavelength (ΔC)

ENVELOPE (envelope curve)

method

Spectral width (Δλ)

Threshold

Envelope curve

Optical power

Threshold (bottom)

RMS/PEAK RMS
method

Optical power

Spectral width (Δλ)

Wavelength

Threshold

Wavelength

Threshold

(peak)

Center

wavelength (ΔC)

In the RMS method, the

spectral width (Δλ) is

calculated from the waveform
within the threshold value. In
the peak RMS method, the

spectral width (Δλ) is

calculated from the mode
peak value within the
threshold value. For the
calculation formula, see
appendix 2.

1-36

REPEAT SINGLE

AUTO

CENTER

SWEEP

SETUP

MARKER

USER

UNDO/
LOCAL

REMOTE

HELP

SPAN

RESOLN

ZOOM

PEAK

SEARCH

SYSTEM

PRT
SCN

STOP

LEVEL

SENS

TRACE

ANALYSIS

FILE

APP

PRESET

ANALYSIS -> Spec Width

Threshold (THRESH), envelope curve
(ENVELOPE), RMS, peak RMS, notch
(NOTCH)

IM AQ6380-01EN

Wavelength

Optical power

Peak level

1.3 Analyzing the Optical Spectrum

SMSR and OSNR

SMSR is an abbreviation for side-mode suppression ratio. SMSR represents the level difference
between the mode peak and a side mode.
OSNR is an abbreviation for optical signal to noise ratio. OSNR represents the level difference
between the mode peak and noise. Both analysis items can be used to confirm the properties of
spectral waveforms with steep peaks such as DFB-LD.

OSNR

SMSR

Noise
level

Note

The light source (DFB-LD) analysis also includes an SMSR.

1

Features

AUTO

CENTER

SWEEP

SETUP

MARKER

USER

REMOTE

UNDO/

LOCAL

FUNCTION

REPEAT SINGLE

SPAN

RESOLN

ZOOM

PEAK

SEARCH

SYSTEM

PRT

HELP

SCN

STOP

LEVEL

SENS

TRACE

ANALYSIS

FILE

APP

PRESET

ANALYSIS -> Analysis 1

SMSR

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1-37

Optical power

Wavelength line

Wavelength line

POWER value

FUNCTION

1.3 Analyzing the Optical Spectrum

POWER

This function integrates the level values of a spectral waveform and calculates the power (POWER).
The integral range is the entire spectrum. When Search/Ana Marker L1-L2 is set to On in the
ANALYSIS menu, the integral range is set to the range between the wavelength line markers. For
the calculation formula of the power value, see “POWER analysis function” in Appendix 3.

marker L1

marker L2

Integral range

Wavelength

Note

The light source (DFB-LD, FP-LD, LED) analysis also includes power.

REPEAT SINGLE

AUTO

CENTER

SWEEP

SPAN

RESOLN

STOP

LEVEL

SENS

1-38

SETUP

MARKER

USER

REMOTE

UNDO/
LOCAL

ZOOM

SEARCH

SYSTEM

HELP

PEAK

PRT
SCN

TRACE

ANALYSIS

FILE

APP

PRESET

ANALYSIS -> Analysis 1

POWER

IM AQ6380-01EN

FUNCTION

1.3 Analyzing the Optical Spectrum

SSER/STSSER

SSER

SSER stands for Signal to Spontaneous Emission Ratio. It is the signal light to spontaneous
emission light ratio, which is the difference in level between the mode peak and spontaneous
emission light.

STSSER

STSSER stands for Signal to Total Source Spontaneous Emission Ratio. It is the signal light to total
spontaneous emission light ratio, which is the difference in level between the mode peak and total
spontaneous emission light.

Light source (DFB-LD, FP-LD, LED, ITLA) spectral analysis

Light source parameters including spectral line width, SMSR, power, and SSER/STSSER explained
earlier in this section, can be analyzed collectively.

REPEAT SINGLE

AUTO

CENTER

SPAN

STOP

LEVEL

1

Features

SWEEP

SETUP

MARKER

USER

REMOTE

UNDO/
LOCAL

RESOLN

ZOOM

SEARCH

SYSTEM

HELP

PEAK

PRT
SCN

SENS

TRACE

ANALYSIS

FILE

APP

PRESET

ANALYSIS -> Analysis 1

DFB-LD, FP-LD, LED, ITLA

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1-39

Optical power

FUNCTION

1.3 Analyzing the Optical Spectrum

WDM signal spectral analysis

This function calculates the center wavelength (λ), level, noise, SNR, and other parameters of each

channel from the measured WDM signal spectral waveforms. For an explanation and calculation
formula of each parameter, see appendix 4.

λ1 λ2 λ3

Level
value

SNR

SPACING

Noise

Wavelength

Analysis item Description

No.1, No.2, ... Channel number
WAVELENGTH Center wavelength (λ) of the channel
LEVEL Level value of the channel (difference between the peak level and noise level)
OFFSET WL Relative wavelength to the wavelength of the reference channel (REF). Specify

REF with a parameter.

OFFSET LVL Relative level to the level of the reference channel (REF) Specify REF with a

parameter.
SPACING Wavelength spacing to the adjacent channel
LVL DIFF Level difference from then adjacent channel
NOISE Noise level of the channel
SNR SNR value of the channel
GRID WL Grid wavelength closest to the center wavelength of the channel
MEAS WL Center wavelength (λ) of the channel
REL WL Relative wavelength to the nearest grid wavelength of the channel

1-40

AUTO

CENTER

SWEEP

SETUP

MARKER

USER

REMOTE

UNDO/
LOCAL

REPEAT SINGLE

SPAN

RESOLN

ZOOM

PEAK

SEARCH

SYSTEM

PRT

HELP

SCN

STOP

LEVEL

SENS

TRACE

ANALYSIS

FILE

APP

PRESET

ANALYSIS -> Analysis 2

WDM

IM AQ6380-01EN

Optical power

FUNCTION

1.3 Analyzing the Optical Spectrum

Optical amplifier analysis (Gain, NF analysis)

This function calculates the gain and noise figure (NF) of the optical amplifier from the spectral
waveform of the input light to the optical amplifier (Trace A) and the spectral waveform of the
output light from the optical amplifier (Trace B). For an explanation and calculation formula of each
parameter, see appendix 5.

Removal of the
signal light SE
component
contained in the
optical amplifier
output light

Signal
light

Analysis item Description

WAVELENGTH Center wavelength (λ) of the channel
INPUT LVL Level value of the channel signal light
OUTPUT LVL Level value of the channel output light
ASE LVL Level value of the channel ASE light
RESOLN Measurement resolution of the channel
GAIN Gain of the channel
NF NF of the channel

Gain

Output
light

ASE level

Wavelength

1

Features

AUTO

CENTER

SWEEP

SETUP

MARKER

USER

REMOTE

UNDO/
LOCAL

REPEAT SINGLE

SPAN

RESOLN

ZOOM

PEAK

SEARCH

SYSTEM

PRT

HELP

SCN

STOP

LEVEL

SENS

TRACE

ANALYSIS

FILE

APP

PRESET

ANALYSIS -> Analysis 2

EDFA-NF

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1-41

FUNCTION

1.3 Analyzing the Optical Spectrum

Optical filter analysis

This function measures the spectral waveform of the input light to the optical filter (Trace A)
and the spectral waveform of the output light from the optical filter (Trace B) and measures the
characteristics of the optical filter from their difference spectrum (Trace C = A – B). It analyzes the
single-channel and multi-channel (WDM signal) spectral waveforms.

REPEAT SINGLE

AUTO

STOP

CENTER

SWEEP

SETUP

MARKER

SPAN

RESOLN

ZOOM

PEAK

SEARCH

LEVEL

SENS

TRACE

ANALYSIS

ANALYSIS -> Analysis 2

USER

SYSTEM

FILE

FILTER-PK, FILTER-BTM, WDM FIL-PK,
WDM FIL-BTM

APP

REMOTE

UNDO/
LOCAL

HELP

PRT
SCN

PRESET

Before analysis

Using the trace function, draw the spectral waveform of the input light in trace A and the
spectral waveform of the output light in trace B. Display the difference waveform (C = A –
B(LOG)) on trace C. Then, perform the analysis on the difference waveform of trace C. For
instructions on how to use the trace function, see section 1.2.
The following illustrations of single-channel and multi-channel optical filter characteristics use
differential waveforms.

1-42

Optical power

Input optical spectrum to the
optical filter (Trace A)

Output optical spectrum from the
optical filter (Trace B)

Transmission
characteristics of the
optical filter (Trace C = A
– B (LOG))

Wavelength

IM AQ6380-01EN

Optical power

Center wavelength

Wavelength

Optical power

Center wavelength

Bottom wavelength

1.3 Analyzing the Optical Spectrum

Single-channel filter characteristics

A single-channel spectral waveform is analyzed. For an explanation and calculation formula
of each parameter, see “FILTER PEAK analysis function” and “FILTER BOTTOM analysis
function” in Appendix 6.

FILTER-PK

Ripple
width

Cross­talk

Peak wavelength

Peak level

Threshold

Wavelength

Spectral width

1

Features

Analysis item Description

PEAK WL Peak wavelength
CENTER WL Center wavelength
SPECTRUM WIDTH Spectral width
RIPPLE WIDTH Ripple width
CROSS TALK Crosstalk

FILTER-BTM

Notch width

Cross­talk

Threshold

Bottom level

IM AQ6380-01EN

Analysis item Description

BOTTOM LVL Bottom level
BOTTOM WL Bottom wavelength
CENTER WL Center wavelength
NOTCH WIDTH Notch width (displayed as SPEC WIDTH on the screen)
CROSS TALK Crosstalk

1-43

Optical power

Peak level

Crosstalk

Test band

1.3 Analyzing the Optical Spectrum

Multi-channel filter characteristics

A multi-channel spectral waveform is analyzed. For an explanation and calculation formula of
each parameter, see “WDM FILTER PEAK analysis function” and “WDM FILTER BOTTOM
analysis function” in Appendix 6.

WDM FIL-PK

No.1

No.4

No.2 No.3

Peak wavelength

Wavelength

XdB stopband
(SB)

Reference wavelength (depending on
the selected algorithm)

Threshold
(XdB)

XdB center
wavelength
(CTR)

Test band

Threshold
(XdB)

XdB WIDTH
(WD)

Threshold
(XdB)

Ripple width

value

1-44

XdB passband
(PB)

Analysis item Description

No.1, No.2, ... Channel number
NOMINAL WL Reference wavelength of the channel
PK WL Peak wavelength of the channel
PK LVL Peak level of the channel
XdB WD XdB width of the channel
XdB CTR XdB center wavelength of the channel
XdB SB XdB stop band of the channel
XdB PB XdB pass band of the channel
RIPPLE WIDTH Ripple width of the channel
CROSS TALK Crosstalk of the channel

IM AQ6380-01EN

Optical power

XdB center

Test band

1.3 Analyzing the Optical Spectrum

WDM FIL-BTM

No.1

No.2 No.3

Wavelength

Reference wavelength (depending on
the selected algorithm)

No.4

wavelength (CTR)

XdB notch width
(NW)

Threshold (XdB)
(peak)

Threshold (XdB)
(bottom)

XdB stopband
(SB)

Threshold
(XdB)

Test band

1

Features

Bottom wavelength

Bottom level

XdB elimination
band

Analysis item Description

No.1, No.2, ... Channel number
NOMINAL WL Reference wavelength of the channel
BTM WL Bottom wavelength of the channel
BTM LVL Bottom level of the channel
XdB NB XdB notch width of the channel
XdB CTR XdB center wavelength of the channel
XdB SB XdB stop band of the channel
XdB EB XdB elimination band of the channel
RIPPLE WIDTH Ripple width of the channel
CROSS TALK Crosstalk of the channel

Crosstalk value

Ripple width

Threshold
(XdB)

IM AQ6380-01EN

1-45

Optical power

Peak level

1.3 Analyzing the Optical Spectrum

WDM SMSR analysis

This function calculates the SMSR of each channel from the measured WDM signal spectral
waveforms. For an explanation and calculation formula of each parameter, see appendix 4.

No.1 No.2 No.3 No.4 No.5 No.6

No.7

Threshold

Side mode peak level

SMSR

(XdB)

XdB WIDTH
(WD)

Side mode peak

Wavelength

wavelength

Peak wavelength

Analysis item Description

No.1, No.2, ... Channel number
PK WL Peak wavelength of the channel
PK FREQ Peak frequency of the channel
PK LVL Peak level of the channel

-XdB WD XdB width of the channel
2ND PK WL Side mode peak wavelength of the channel
2ND PK FREQ Side mode peak frequency of the channel
2ND PK LVL Side mode peak level of the channel
SMSR Level difference between the mode peak and a side mode of the channel

1-46

AUTO

CENTER

SWEEP

SETUP

MARKER

USER

REMOTE

UNDO/
LOCAL

FUNCTION

REPEAT SINGLE

SPAN

RESOLN

ZOOM

PEAK

SEARCH

SYSTEM

PRT

HELP

SCN

STOP

LEVEL

SENS

TRACE

ANALYSIS

FILE

APP

PRESET

ANALYSIS -> Analysis 2

WDM SMSR

IM AQ6380-01EN

1.3 Analyzing the Optical Spectrum

Function menus

ANALYSIS key

“Spectral width”, “SMSR and OSNR”, “POWER”,

“Light source (DFB-LD, FP-LD, LED, ITLA) spectral analysis ”,

“WDM signal spectral analysis”, “Optical amplifier analysis (Gain, NF analysis)”,

“WDM SMSR analysis”,“Optical filter analysis” in Features

Selecting the spectral width analysis (Spec Width)

Select the spectral width analysis type from five options.

Selecting the batch analysis of SMSR, POWER, and light source (Analysis 1)

Select the analysis type from five options. SMSR and POWER are separate analysis functions.
In the batch analysis of light sources, the content to be analyzed for each light source (DFB­LD, FP-LD, LED) is fixed. The content to be analyzed consists of the spectrum width, SMSR,
POWER, and OSNR items.

Batch analysis of light sources

Light source type Analysis item

DFB-LD Center wavelength, spectral width, SMSR, POWER, OSNR
FP-LD Center wavelength, spectral width, POWER, number of modes
LED Center wavelength, spectral width, POWER

1

Features

DFB-LD

Center wavelength, spectral width (-XdB WIDTH)

This function calculates the spectral width (Δλ) and center wavelength (λC) at a level that

is lower than the level of the peak wavelength (λP) by the threshold of XdB (e.g., –20 dB).

For an explanation and calculation formula of each parameter, see “THRESH method,”

“ENVELOPE (envelope) method,” “RMS method,” and “PEAK RMS method" in appendix 2.

Side mode suppression ratio (SMSR)

This function calculates the difference between the mode peak and a side mode. For
an illustration of SMSR, see the figure on page 1-35. For an explanation and calculation
formula of each parameter, see “SMSR analysis function” in appendix 3.

Center wavelength, spectral width (RMS, PK-RMS)

In the RMS method, the spectral width (Δλ) is calculated from the waveform within the

threshold value. In the peak RMS method, the spectral width (Δλ) is calculated from the

peak value within the threshold value. For an illustration of RMS and PK-RMS (peak
RMS), see the figure on page 1-34. For an explanation and calculation formula of each

parameter, see “RMS method” and “PEAK RMS method” in appendix 2.

Integral of the level value (POWER)

This function integrates the level values of a spectral waveform and calculates the optical
power (POWER). For an illustration of POWER, see the figure under “POWER” on page
1-36. As a parameter, you need to set the integration range for the peak wavelength.

IM AQ6380-01EN

1-47

Wavelength of the peak value

Optical power

Wavelength

1.3 Analyzing the Optical Spectrum

Optical signal to noise ratio (OSNR)

This function calculates the level difference between the mode peak and noise. For an
illustration of OSNR, see the figure on page 1-35. For an explanation and calculation
formula of each parameter, see “Analysis algorithm” and “Automatic parameter setting
function” in appendix 4.

FP-LD

Center wavelength, spectral width (SPECTRUM WIDTH)

This function calculates the spectral width (Δλ) and center wavelength (λC). For an

explanation and calculation formula of each parameter, see “THRESH method,”
“ENVELOPE (envelope) method,” “RMS method,” and “PEAK RMS method" in appendix 2.

Mean wavelength (MEAN WAVELENGTH)

This function calculates the mean wavelength. The mean wavelength is the center position
between two points whose levels are less than the level of the peak value by the threshold
value (20 dB).

Wavelength of the average value

Threshold

Total integral of the level value (TOTAL POWER)

This function integrates the level values of a multi-peak spectral waveform one by one and
calculates the total optical power (POWER). For an explanation of the OFFSET LEVEL
parameter and the calculation formula for POWER, see “POWER analysis function” in
appendix 2.

Number of modes (MODE NO.)

This function calculates the number of modes in a multi-peak spectral waveform. For
an explanation and calculation formula of each parameter, see “THRESH method,”
“ENVELOPE (envelope) method,” “RMS method,” and “PEAK RMS method" in appendix 2.

1-48

IM AQ6380-01EN

1.3 Analyzing the Optical Spectrum

LED

Center wavelength, spectral width (SPECTRUM WIDTH)

This function calculates the spectral width (Δλ) and center wavelength (λC). For an

explanation and calculation formula of each parameter, see “THRESH method,”
“ENVELOPE (envelope) method,” “RMS method,” and “PEAK RMS method" in appendix 2.

Mean wavelength (MEAN WAVELENGTH)

This function calculates the mean wavelength. The mean wavelength is the center position
between two points whose levels are less than the level of the peak value by the threshold
value (20 dB). For an illustration of the mean wavelength, see the “Mean waveform” figure
for FP-LD.

Total integral of the level value (TOTAL POWER)

This function integrates the level values of a spectral waveform and calculates the total
optical power (POWER). For an explanation of the OFFSET LEVEL parameter and the
calculation formula for POWER, see “POWER analysis function” in appendix 3.

Selecting the analysis of the WDM waveform, optical amplifier characteristics, and
optical filter characteristics (Analysis 2)

Select the analysis type from six options.

1

Features

Executing an analysis (Analysis Execute)

This function executes the selected analysis.

Threshold value for spectral width analysis (Spec Width Thresh)

Set the threshold value used in the spectral width analysis. Set the value separately for each
analysis type.

Setting the analysis parameters (Parameter Setting)

For the analysis (Spec Width, Analysis 1, Analysis 2) selected in the ANALYSIS menu, you
can set the analysis parameter that is selected in each key menu. For the meanings of the
parameters, see appendix 2 to appendix 6.

Analysis result display screen (Switch Display)

Select the format of the display screen that shows the results of the analysis (Analysis 2) of
the WDM waveform, optical amplifier characteristics, and optical filter characteristics.

Executing auto analysis (Auto Analysis)

Each time the instrument sweeps and updates the measurement spectral data, the analysis
selected in each key menu is executed for the analysis (Spec Width, Analysis 1, Analysis 2)
selected in the ANALYSIS menu.

IM AQ6380-01EN

Analysis between wavelength line markers (L1 and L2) (Search/Ana Marker L1-L2)

Peak search, bottom search, and calculation of analysis function (ANALYSIS key) can be
performed in the area between wavelength line markers L1 and L2. Set the wavelength line
markers using Line Marker 1 and Line Marker 2 in the MARKER menu.

1-49

1.3 Analyzing the Optical Spectrum

Search in the waveform display zoom range (Search/Ana Zoom Area)

Peak search, bottom search, and calculation of analysis function (ANALYSIS key) can be
performed in the zoom range of the waveform display. Set the zoom range using Zoom
Center, Zoom Span, Zoom Start, and Zoom Stop in the ZOOM menu.

Editing the grid table (Grid Setting)

Set the WDM frequency table (grid table) to be referenced inside the instrument when
performing spectral waveform analysis.

1-50

IM AQ6380-01EN

1.4 Saving and Loading Data

Date and time

Measurement
conditions

Header and
data of analysis
data

Saving and loading

Waveform data (Trace)

You can save to a file the data of a specified trace from the measured spectrum waveforms (Traces
A to G). You can also load a saved file into a specified trace and display the waveforms.

Waveform data (all traces) (All Trace)

All trace data (TraceA to G) is collectively saved in a file. The data format is binary and CSV. You
can also load saved data into the instrument and display the waveforms.

Screen capture (Graphics)

You can capture the screen and save it in a specified image format (bmp, jpg, png). You can view
saved screen captures on the preview screen.

Setting data (Setting)

You can save the instrument’s measurement conditions and function menu states to a file in binary
format. You can also load a saved setting file to change the settings of the instrument.

1

Features

Analysis results (Data)

You can save analysis results, the time when the data was saved, and waveform data in CSV
format. You can select the items to save from the items in the following figure. You can also view
the contents of the saved data file on the preview screen.

Label

Data area

Waveform
data

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1.4 Saving and Loading Data

Function menus

FILE key

Save (Save)

You can save the target data in a specified folder.

Load (Load)

You can select the target data from a file list and load it.

Target data selection (Item Select)

Select the target data from waveform data (Trace), waveform data (all traces) (All Trace),
screen capture (Graphics), setting data (Setting), and analysis results (Data).

Auto file name format (Auto File Name)

The default name for saving files is automatically set. You can set the file name format to
number or date and time.

Removing USB storage devices (Remove USB Storage)

You can remove USB storage devices (USB memory, external hard disk).

“Saving and Loading” in Features

File operation (File Operation)

The following file operations are available on the file operation window.

• Copying, moving, and deleting files (Copy, Move, Delete)

You can copy, move, or delete the files and folders in the internal memory and USB
storage devices.

• Renaming files (Rename)

You can rename existing files and folders.

• Making folders (New Folder)

You can make destination folders that files can be saved or moved to. You can assign
names to those folders.

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1.5 System Setup

Function menus

SYSTEM key

Alignment adjustment (Optical Alignment)

This function adjusts the optical axis of the monochromator (spectrometer) used inside the
instrument. When you execute this function, the optical axis is adjusted automatically using
the reference light source built into the instrument. For the procedure, see section 9.3.

Wavelength calibration (Wavelength Calibration)

Wavelength calibration can be performed using the reference light source built into the
instrument. Wavelength calibration can also be performed using an external light source. For
the procedure, see section 9.3.

Wavelength shift (Wavelength Shift)

This function sets the amount of wavelength shift. When the wavelength shift is changed, the
specified value is added to the display value on the wavelength axis. This function is used
for purposes such as correcting differences in wavelength display values among different
measurement instruments.

1

Features

Level shift (Level Shift)

This function sets the amount of level shift. When the level shift is changed, the specified
value is added to the display value on the level axis. It is used to correct the loss of external
isolators, filters, or other devices connected to the instrument.

Wavelength resolution calibration (Res BW Calibration)

The wavelength resolution can be calibrated using an external light source as a reference
light source. The instrument measures the equivalent noise bandwidth at each resolution
setting and uses the measured value as the resolution bandwidth of the instrument. For the
procedure, see section 3.6 in the AQ6380 Getting Started Guide (IM AQ6380-02EN).

Switching the wavelength display (Wavelength in)

For the wavelength values to be displayed, set whether to display the value in air or the value
in vacuum.

Remote interface (Remote Interface)

Select the connection method for remotely controlling the instrument. Select from GP-IB,
NETWORK (SOCKET), and NETWORK (VXI-11).

GP-IB setting (GP-IB Setting)

GP-IB address (My Address)

Set the instrument address.

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Command format (Command Format)

Select whether to use AQ6380 commands or AQ6317 compatible commands for remote
control.

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1.5 System Setup

Ethernet settings (Network Setting)

TCP/IP settings (TCP/IP Setting)

Set the IP address and subnet mask.

Port number (Remote Port No.)

When Remote Interface is set to ETHERNET (SOCKET), specify the port number to use
for remote control.

Command format (Command Format)

Select whether to use AQ6380 commands or AQ6317 compatible commands for remote
control.

Login information for remote control (Remote User Account)

When Remote Interface is set to ETHERNET (SOCKET), set the user name and password
to use for starting remote control.

Remote monitor (Remote Monitor)

You can use the ETHERNET port to monitor the instrument screen or control the
instrument from a PC over a network. To use this feature, you need remote monitoring
software (not included).

Session timeout (Timeout)

When Remote Interface is set to ETHERNET (SOCKET), if no communication takes place
for the specified time in remote mode, the communication is automatically disconnected,
and the mode changes to local.

Turning off the display (Display Off)

This function temporarily turns the display off.

Trigger input (Trigger Input Mode)

The instrument starts spectral data sampling or sweeping using an external signal as a trigger.
For the procedure, see section 3.4.

Trigger output (Trigger Output Mode)

The instrument outputs trigger signals from the trigger output terminal on the rear panel only
while the instrument is sweeping. For the procedure, see section 3.5.

Auto internal amplifier offset (Auto Offset Setting)

Offset adjustment of the amplifier used inside the instrument can be automatically performed
at regular intervals.

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Setting the UNCAL Mark and WARNING indicator (Uncal Warning)

You can turn off the warning message that is displayed on the instrument screen when the
instrument is in an Uncal state, such as when the number of samples is too small for the
sweep span (SPAN).

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1.5 System Setup

Turning off the buzzer (Buzzer)

You can turn off the buzzer sound that is generated when you tap the instrument screen or
when a warning messages displayed.

Number of digits in the numeric display (Level Display Digit)

You can set the number of displayed digits for the level values displayed in the instrument’s
data area.

Display color (Color Mode)

You can set the instrument’s display color mode to color or black-and-white.

Language (Language)

You can change the language of the menu display, warning messages, and so on. The
language used in the waveform display area, data area, parameter setting window, and so on
is fixed to English (cannot be changed).

Setting the clock (Set Clock)

You can set the clock. For the procedure, see section 4.5 in the AQ6380 Getting Started
Guide (IM AQ6380-02EN).

1

Features

Registering the user-defined menu (User Key Define)

You can register frequently used menus in the USER menu.

Locking the keys (Operation Lock)

This function disables menu operations except for the USER menu.

Clearing parameters (Parameter Initialize)

You can initialize the settings in each menu, parameter values (values displayed in setting
windows), alignment adjustment value, wavelength calibration value, and resolution calibration
value.

Viewing the system information (System Information)

You can view the software version, product suffix code, and network information (e.g., IP
address). You can also update the firmware and view the open source software (OSS) license
information.

Test mode (Test Mode)

The test mode is used to adjust the instrument at the factory and is not used in ordinary
situations.

IM AQ6380-01EN

Shutdown (Shut Down)

This function turns off the instrument.

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1.5 System Setup

UNDO/LOCAL key

Press UNDO/LOCAL to undo the last operation. An Undo menu will appear on the screen. You
can undo or redo up to five operations.
UNDO soft key: Undoes the last operation
REDO soft key: Cancels the last undo operation

AUTO

FUNCTION

REPEAT SINGLE

STOP

CENTER

SWEEP

SETUP

MARKER

USER

REMOTE

UNDO/
LOCAL

SPAN

RESOLN

ZOOM

PEAK

SEARCH

SYSTEM

HELP

PRT
SCN

LEVEL

SENS

TRACE

ANALYSIS

FILE

APP

PRESET

UNDO/LOCAL

UNDO, REDO

The function of the key varies depending on the state the instrument is in when you press
UNDO/LOCAL.
The following table shows the functions of the UNDO/LOCAL key depending on the instrument
state.

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Instrument state Function

Undo action available If you press UNDO immediately after changing a parameter

setting or changing or deleting data, the previous operation
is canceled, and the instrument returns to the previous
state.

During user key registration If you press UNDO while registering a user key, the

registration mode is canceled, and the soft key menu that

was displayed when you pressed SYSTEM appears again.
Under remote control from an external PC
(REMOTE indicator is on)

The instrument returns to local mode from remote mode.

The REMOTE indicator turns off.

USER key

Up to 24 menus can be registered as user keys.
By registering frequently used menus as user keys, you can access them simply by opening
the USER menu.

IM AQ6380-01EN

1.6 Application Feature (APP Feature)

the explanations in sections 6.5 and 6.6.

Example of an FP-LD test

Overview

The application feature (APP feature) is an expansion feature used to install and uninstall various
dedicated software applications designed for this instrument. Various applications are available
to assist with the measurement condition setup, analysis, and data saving according to the
measurement target, such as DFB-LD, LED, and other light signals and WDM signals.
Add-on applications can be downloaded from YOKOGAWA webpage and installed to expand the
features of the instrument.

By factory default, the following applications are preinstalled in the instrument.

• WDM Test

• FP-LD Test

• DFB-LD Test

• LED Test

• Optical fiber end face check

• Programming

• Data logging

• Maintenance information export

1

Features

WDM/FP-LD/DFB-LD/LED Test

The setting items required for various tests and the display and save operations are consolidated
in a single test screen. The contents that can be obtained through analysis are the same as those
explained in section 6.5 and 6.6. In addition, the measurement conditions operated on the test
screen are items that are often used during testing. The screen displays one trace. Waveforms that
have undergone tests can be saved as files by tapping.

Analysis results

You will get the same results as described in

Execute a measurement.

The procedure described in section 3.2
is included.

Measurement conditions
(resolution, sensitivity, span)

Typical items are incorporated from the
procedures in chapter 2.

Analysis conditions (calculation
algorithm)

Typical items are included from the
procedures in chapter 6 and the
parameters in the appendix.

Display operation

Switches the unit of the scale
display The main scale items of
section 2.1 are included.

Saves waveform and analysis data

Items of sections 7.2, 7.4, and 7.6 are included.

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1.6 Application Feature (APP Feature)

DI-1000/DI-2000 (Lightel)

End face of the optical fiber cable

Optical fiber end face check (FIP)

You can use a fiber inspection probe recommended by YOKOGAWA to take a photograph that
shows the state of a fiber end face. You can display this photograph on the instrument screen. You
can also save the photograph.

Fiber inspection probe Optical fiber cable

Recommended product:

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IM AQ6380-01EN

1.6 Application Feature (APP Feature)

Programming (PROGRAM)

Program functions allow control of this device without the need for an external PC. The program
function provides function commands that work equivalently to the keys in the FUNCTION section
of the front panel. By assembling each command and creating a program with the program function,
you can automate the operation of the function menu and parameters. For details about the
program functions, see the separate user's manual, "Optical Spectrum Analyzer Remote Control".

Data Logging (DATA LOGGING)

The analysis data logging function measures and records WDM analysis, DFB-LD analysis, and
peak data at regular intervals. The recorded data can be shown on the screen in tables or graphs.
In addition, the contents in tables can be saved to a file in CSV format.
The following types of data are recorded for WDM analysis and peaks.

• WDM analysis: Wavelength, level, SNR (signal-to-noise ratio)

• Peak: Wavelength, level

Maintenance information export (Support file builder)

This is a function that allows you to create a support file for us to investigate the cause if a problem
or malfunction occurs while you are using this instrument.
In the event of a problem or malfunction, your YOKOGAWA dealer may ask you to create and send
a support file. If you are asked to do so, please create a ZIP file with this function and send the file.
You do not need to check the contents of the file.

1

Features

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1.6 Application Feature (APP Feature)

Function menus

APP key

“Maintenance information export (Support file builder)” in Features

Information (Information)

You can view an overview of the selected application.

Running the application feature (Execute)

You can run the selected application.

Installation (Install)

You can install application installer files (.apl files) stored in the shared folder or USB memory
device.

Uninstallation (Uninstall)

You can uninstall applications installed in the instrument.
You can also uninstall preinstalled applications.

“WDM/FP-LD/DFB-LD/LED analysis test”,

“Optical fiber end face check”,“Programming (PROGRAM)”,

“Data Logging (DATA LOGGING)”,

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1

Chapter 2 Setting the Measurement Conditions

2.1 Measurement Wavelength (Frequency) Range

Procedure

Setting the horizontal scale

Setting the horizontal scale unit to wavelength or frequency

1.

Press SETUP. The Setup menu appears.

2.

Tap More 1/2. The More 2/2 menu appears.

3.

Tap Horizontal Scale nm/THz. The horizontal scale unit changes to nm or THz.

2

Setting the Measurement Conditions

Setting the measured wavelength to wavelength in air or wavelength in
vacuum

1.

Press SYSTEM. The SYSTEM menu appears.

2.

Tap Wavelength in Air/Vacuum. A confirmation message appears.

3.

Tap Yes. To cancel, tap No.

When you tap Yes, the displayed waveforms, moving markers, and fixed markers will be cleared.

Note

• This function takes effect when a measurement is executed after the setting is
changed. It is not applied to the waveform that has already been measured.

• When the setting is changed, or is displayed in Air mode or in
Vacuum mode, respectively, at the bottom of the waveform screen.

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2-1

Setting example (for center wavelength)

2.1 Measurement Wavelength (Frequency) Range

Setting the center wavelength or center frequency

There are four ways to set the center wavelength or center frequency:

• Set the center wavelength or center frequency on the Center menu

• Set the start and stop wavelengths or start and stop frequencies on the Center menu

• Set using one-action

• Set the center wavelength or center frequency to the moving marker wavelength or frequency

Switching between the wavelength display and frequency display

Switch the horizontal scale unit between nm and THz using the horizontal scale settings
on page 2-1. The setup item switches between wavelength display and frequency display
according to the setting.

Setting the center wavelength or center frequency on the Center menu

1.

Press CENTER. The Center menu appears.

2.

Tap Center. The CENTER setting window appears.

3.

Enter the center wavelength or center frequency in the displayed window.

For instructions on how to select items and how to set values, see chapter 4 in the Getting Started

Guide.

Note

• The assigned value is applied to the measurement conditions area.

• When a setting is changed,

• If you enter a value outside the setting range, the closest allowed value is assigned.

appears in the measurement condition area.

2-2

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1

Setting example (for start wavelength)

2.1 Measurement Wavelength (Frequency) Range

Setting the start and stop wavelengths or start and stop frequencies on
the Center menu

1.

Press CENTER. The Center menu appears.

Setting the start wavelength or start frequency

2.

Tap Start. A START setting window appears.

3.

Enter the start wavelength or start frequency in the displayed window.

For instructions on how to select items and how to set values, see chapter 4 in the Getting Started

Guide.

Setting the stop wavelength or stop frequency

4.

Tap Stop. A STOP setting window appears.

5.

Enter the stop wavelength or stop frequency in the displayed window.

For instructions on how to select items and how to set values, see chapter 4 in the Getting Started

Guide.

2

Setting the Measurement Conditions

Note

• The assigned value is applied to the measurement conditions area.

• When a setting is changed,

• If you enter a value outside the setting range, the closest allowed value is assigned.

appears in the measurement condition area.

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2-3

2.1 Measurement Wavelength (Frequency) Range

Setting using one-action

1.

Press CENTER. A Center menu appears.

2.

Tap one of the following four menus.

Tap Peak WL -> Center:

The center wavelength or center frequency is set to the peak wavelength or peak frequency.

Tap Mean WL -> Center:

The center wavelength or center frequency is set to RMS 20dB center wavelength or center

frequency.

Tap Auto Center Off On to select On:

The peak wavelength or peak frequency of the measured waveform is assigned automatically to

the center wavelength or center frequency for each sweep.

Tap View Scale -> Measure:

The center wavelength or center frequency is set to the currently displayed ZOOM scale (see

section 4.1). This is used in the measurement of the next sweep.

Set to the peak value

Set to the RMS 20dB center wavelength

Automatically set for each sweep

Set to the currently displayed zoom scale

Setting the center wavelength or center frequency to the moving marker
wavelength or frequency

1.

Press MARKER. The Marker menu appears.

2.

With the moving marker (see section 5.1) displayed, tap Marker -> Center.

The center wavelength or center frequency is set to the moving marker wavelength or frequency.

The displayed waveform is redrawn according to the set center wavelength or center frequency.

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1

Setting example (wavelength sweep span)

2.1 Measurement Wavelength (Frequency) Range

Setting the sweep span

There are four ways to set the sweep span:

• Set the sweep span in the Span menu

• Set the start and stop wavelengths or start and stop frequencies on the Span menu

• Set using one-action

• Set the measurement sweep span to the span between line markers L1 and L2

Switching between the wavelength display and frequency display

Switch the horizontal scale unit between nm and THz using the horizontal scale settings
on page 2-1. The setup item switches between wavelength display and frequency display
according to the setting.

Setting the sweep span in the Span menu

1.

Press SPAN. The Span menu appears.

2.

Tap Span. A SPAN setting window appears.

3.

Enter the sweep span in the displayed window.

For instructions on how to select items and how to set values, see chapter 4 in the Getting Started

Guide.

2

Setting the Measurement Conditions

Note

• The assigned value is applied to the measurement conditions area.

• When a setting is changed,

• If you enter a value outside the setting range, the closest allowed value is assigned.

appears in the measurement condition area.

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2-5

Setting example (for start wavelength)

2.1 Measurement Wavelength (Frequency) Range

Setting the start and stop wavelengths or start and stop frequencies on
the Span menu

1.

Press SPAN. The Span menu appears.

Setting the start wavelength or start frequency

2.

Tap Start. A START setting window appears.

3.

Enter the start wavelength or start frequency in the displayed window.

For instructions on how to select items and how to set values, see chapter 4 in the Getting Started

Guide.

Setting the stop wavelength or stop frequency

4.

Tap Stop. The STOP setting window appears.

5.

Enter the stop wavelength or stop frequency in the displayed window.

For instructions on how to select items and how to set values, see chapter 4 in the Getting Started

Guide.

Note

• The assigned value is applied to the measurement conditions area.

• When a setting is changed,

• If you enter a value outside the setting range, the closest allowed value is assigned.

appears in the measurement condition area.

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1

2.1 Measurement Wavelength (Frequency) Range

Setting using one-action

1.

Press SPAN. The Span menu appears.

2.

Tap one of the following two menus.

Tap Δλ -> Span:

The sweep span is set to RMS 20 dB span × 6 of the active trace waveform.

Tap View Scale -> Measure:

The sweep span is set to the currently displayed ZOOM scale (see section 4.1). In the next sweep,

the displayed waveform will be redrawn according to the set sweep span.

Set to RMS 20dB × 6

2

Setting the Measurement Conditions

Set to the currently displayed zoom scale

Setting the measurement sweep span to the span between line markers
L1 and L2

1.

Press MARKER. The Marker menu appears.

2.

Tap More 1/3. The More 2/3 menu appears.

3.

With line markers L1 and L2 displayed (see section 5.2), tap Marker L1-L2 -> Span. The

sweep span is set to the span between line markers L1 and L2.

Note

• If only line marker L1 is displayed, the sweep stop position is set to the
right edge of the screen. If only L2 is displayed, the sweep start position
is set to the left edge of the screen.

• Marker L1-L2 -> Span cannot be used under the following conditions.

• When both L1 and L2 are off

• When the span of the active trace is 0 nm

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2-7

2.1 Measurement Wavelength (Frequency) Range

Explanation

Horizontal scale

Wavelength display mode

• Measured waveforms are displayed with the horizontal scale set to wavelength.

• The measurement scale and display scale are set in terms of wavelength.

• The horizontal scale unit of marker values and analysis results is wavelength.

Frequency display mode

• Measured waveforms are displayed with the horizontal scale set to frequency.

• The measurement scale and display scale are set in terms of frequency.

• The horizontal scale unit of marker values and analysis results is frequency.

Displayed units for horizontal scale and marker values

The unit displayed for marker values (wavelength or frequency) can be set separately from
the waveform display’s horizontal scale unit set with Horizontal Scale nm THz under SETUP.
(Default: nm)
(For example, it is possible to set the horizontal scale to frequency display mode and marker
values to wavelength display mode.)

Note

The Marker Unit nm THz setting changes in sync with the Horizontal Scale setting, but changing the
Marker Unit nm THz setting will not change the Horizontal Scale setting.

Center wavelength or center frequency

Switch the horizontal scale unit between nm and THz using the horizontal scale settings described
on page 2-1. The setup item switches between wavelength display and frequency display according
to the setting.

Center wavelength

You can set the value between 1200.000 nm and 1650.000 nm.
When COARSE is selected, you can change the value in steps of 1 nm. Otherwise, you can
set the value in steps of 0.1 nm.

Start wavelength

You can set the value between 975.000 nm and 1650.000 nm.

Stop wavelength

You can set the value between 1200.000 nm and 1875.000 nm.

2-8

Center frequency

You can set the value between 181.5000 THz and 250.0000 THz.
When COARSE is selected, you can change the value in steps of 0.1 THz. Otherwise, you
can set the value in steps of 0.01 THz.

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1

2.1 Measurement Wavelength (Frequency) Range

Start frequency

You can set the value between 147.2500 THz and 250.0000 THz.

Stop frequency

You can set the value between 181.5000 THz and 284.2500 THz.

Note

• When you set the start wavelength or stop wavelength, the sweep span will change because the
other wavelength does not change. The center wavelength will also change. Likewise, when you
set the start frequency or stop frequency, the sweep span and center frequency will change.

• Changing the center wavelength or center frequency will not change the sweep span.

One-action

This is a general term for the operations that use data from the active trace waveform to set
measurement conditions. To use them, a waveform must be displayed in the active trace.

• Peak WL -> Center

The center wavelength is set to the wavelength at the peak value of the active trace
waveform.
When executed, the specified center wavelength is displayed in a center wavelength setting
window. Then, you can further change the center wavelength.
The same is true for the center frequency.

2

Setting the Measurement Conditions

• Mean WL -> Center

The center wavelength is set to the average (RMS 20 dB center wavelength) of the
spectrum in the range from the peak of the active trace waveform down to the threshold
(20 dB). Then, you can further change the center wavelength.
The same is true for the center frequency.

• Auto Center Off/On

This function sets whether Peak WL -> Center is executed for each sweep.
When this function is set to ON, the peak in the active trace waveform is automatically
detected and assigned to the center wavelength for each sweep.
The active trace must be set to WRITE.

When set to On,

The same is true for the center frequency.

• View Scale -> Measure

The measurement scale (Center, Start, Stop, Span) is set to the currently set zoom scale
(Zoom Center, Zoom Span, Zoom Start, Zoom Stop).
The set scale becomes the measurement scale for the next sweep.

is highlighted at the bottom of the screen.

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2-9

2.1 Measurement Wavelength (Frequency) Range

Moving marker

Marker -> Center

The center wavelength or center frequency is set to the moving marker wavelength. The
displayed waveform is redrawn according to the set center wavelength or center frequency.

Sweep span

Switch the horizontal scale unit between nm and THz using the horizontal scale settings described
in page 2-1. The setup item switches between wavelength display and frequency display according
to the setting.

Wavelength sweep span

You can set the value to 0 or between 0.1 nm and 450.0 nm.
When COARSE is selected, you can change the value in 1-2-5 steps. Otherwise, you can set
the value in steps of 1 nm.

Start wavelength

You can set the value between 975.000 nm and 1650.000 nm.
When COARSE is selected, you can set the value in steps of 1 nm. Otherwise, you can set
the value in steps of 0.1 nm.

Stop wavelength

You can set the value between 1200.000 nm and 1875.000 nm.
When COARSE is selected, you can set the value in steps of 1 nm. Otherwise, you can set
the value in steps of 0.1 nm.

Frequency Sweep Span

You can set the value to 0 or between 0.01 and 68.50 THz.
When COARSE is selected, you can change the value in 1-2-5 steps. Otherwise, you can set
the value in steps of 0.1 THz.

Start frequency

You can set the value between 147.2500 THz and 250.0000 THz.
When COARSE is selected, you can set the value in steps of 0.1 THz. Otherwise, you can set
the value in steps of 0.01 THz.

Stop frequency

You can set the value between 181.5000 THz and 284.2500 THz.
When COARSE is selected, you can set the value in steps of 0.1 THz. Otherwise, you can set
the value in steps of 0.01 THz.

Note

• When you change the sweep span, the start wavelength and stop wavelength will change. The
center wavelength and center frequency will not change.

• When you change the center wavelength, the start wavelength and stop wavelength will change
but the sweep span will not. The same is true when you change the center frequency.

• When you set the start wavelength or stop wavelength, the sweep span will change because the
other wavelength does not change. The center wavelength will also change. Likewise, when you
set the start frequency or stop frequency, the sweep span and center frequency will change.

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1

2.1 Measurement Wavelength (Frequency) Range

One-action

This is a general term for the operations that use data from the active trace waveform to set
measurement conditions. To use them, a waveform must be displayed in the active trace.

• Δλ -> Span

The sweep span is set to six times the spectral width based on the RMS method (20 dB
threshold) of the active trace waveform.

• View Scale -> Measure

The measurement scale (Center, Start, Stop, Span) is set to the currently set zoom scale
(Zoom Center, Zoom Span, Zoom Start, Zoom Stop).
The set scale becomes the measurement scale for the next sweep.

Line markers

Marker L1-L2 -> Span

The sweep span is set to the span between line markers 1 and 2.
You can set the value between 0.1 nm and 450.0 nm (in steps of 0.1 nm).

2

Setting the Measurement Conditions

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2-11

2.2 Wavelength Resolution

Procedure

Switch the horizontal scale unit between nm and THz using the horizontal scale settings described
in section 2.1. The setup item switches between wavelength display and frequency display
according to the setting.

1.

Press RESOLN. The available resolutions are displayed in the menu. A RESOLUTION setting

window also appears.

(The same window appears when you tap

Resolution

Selecting from available values

You can set the value by either of the following methods.

Selecting by tapping the menu

2.

Tap More 1/2 and More 2/2 to view the available values in the menus. Tap the resolution

you want to use.

More 1/2 menu: 0.005nm, 0.01nm, 0.02nm, 0.05nm, 0.1nm, 0.2nm, 0.5nm
More 2/2 menu: 1nm, 2nm

on the Setup menu that appears when you press

SETUP

.)

Selecting on the RESOLUTION setting window

2.

On the RESOLUTION setting window displayed in step 1, tap – or +. On the More 1/2

and More 2/2 menus, the highlighted value changes every time you tap.

3.

When the resolution you want to use is highlighted, tap Exit.

If you entered the value manually, the available resolution closest to the entered value is applied.

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1

2.2 Wavelength Resolution

CUSTOM setting

You can set any value within the setting range.

2.

On the More 2/2 menu, tap Custom. The CUSTOM window appears.

3.

Enter the resolution in the displayed window.

For instructions on how to select items and how to set values, see chapter 4 in the Getting Started

Guide.

4.

Tap Exit.

2

Setting the Measurement Conditions

Note

If the sweep span, sampling points, or resolution setting is inappropriate, is displayed.

What to do when “UNCAL” is displayed

Perform any of the following:

• Decrease the sweep span.

• Increase the sampling points.

• Lower the resolution (increase the value).

• Tap Sampling Points AUTO on the Setup menu.

When the sweep span, sampling points, and resolution settings become appropriate, the
disappears.

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2.2 Wavelength Resolution

Explanation

Available wavelength resolution values

Select from the following:

0.005nm, 0.01nm, 0.02nm, 0.05nm, 0.1nm, 0.2nm, 0.5nm, 1nm, 2nm

For frequency display, select from the following:
1GHz, 2GHz, 4GHz, 10GHz, 20GHz, 40GHz, 100GHz, 200GHz, 400GHz

CUSTOM wavelength resolution

When wavelength display is in use, you can set the value between 0.01 nm and 2.00 nm. For
frequency display, you can set it between 2 GHz and 400 GHz.

Conditions that do not cause UNCAL

The sampling intervals (see section 2.3) that do not cause UNCAL vary depending on the resolution
setting.
For example, to prevent UNCAL from occurring at a resolution of 0.05 nm, the sampling interval
must be 0.002 nm or less. To measure at 20 nm sweep span, the sample points must be set at
least to 20 ÷ 0.002 + 1 = 10001. For details, see “Number of samples (Sampling Points)” in section

1.1.

Ripples in the 1350 to 1450 nm area

Moisture (OH base) present in the air inside the monochromator absorbs light in the 1350 nm to
1450 nm area, resulting in ripples in the measurement waveform. The amount of ripples can be
reduced by setting a coarser resolution, by using the instrument in a low-humidity environment, or
by purging as described in section 3.7 of the Getting Started Guide.

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2.3 Sampling

Setting window when
Sampling Points is tapped

Procedure

There are three ways to set sampling:

• Setting the sampling points

• Setting the sampling interval

• Automatically setting the sampling points or sampling interval according to the sweep span and
resolution setting

1.

Press SETUP. The Setup menu appears.

2.

Tap one of the following three menus.

Tap Sampling Points:

After tapping, set the sampling points. Proceed to step 3.

Tap Sampling Interval:

After tapping, set the sampling interval. Proceed to step 3.

Tap Sampling Points AUTO:

Sampling points or sampling interval is automatically set according to the sweep span and wavelength

resolution setting. This is the end of the procedure.

If you have tapped Sampling Points or Sampling Interval

2

Setting the Measurement Conditions

3.

Note

Enter the sampling points or sampling interval in the displayed window.

For instructions on how to select items and how to set values, see chapter 4 in the Getting Started

Guide.

• If the sweep span, sampling points, or resolution setting is inappropriate, is displayed.

• For instructions on what to do when

is displayed, see section 2.2.

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Sampling interval

Sweep span

Sampling points =

+ 1

2.3 Sampling

Explanation

Sampling points (the number of points to measure in a single
sweep)

Set the number of measurement points per set sweep span.
You can set the value between 101 and 200001.

Relationship between sampling points, sampling interval, and
sweep span

The relationship between sampling points, sampling interval, and sweep span is as follows:

Given the same sweep span, the sampling points are automatically determined when the interval is
known, and vice versa.
For the sweep span setting range, see the explanation in section 2.1, “Measurement Range.”

Note

• Increasing the sampling points or decreasing the sampling interval reduces the sweeping speed.

• Settings that would cause the number of samples in the sweep span to be extremely small cannot be
specified.

• Changing the sampling points also changes the sampling interval accordingly.

Relationship between the sampling interval and wavelength
resolution

If settings are entered such that the sampling interval determined by the sweep span and sampling
points is extremely long relative to the wavelength resolution, data dropout may occur. In such
cases, UNCAL (see section 2.2) is displayed. Enter settings that are appropriate for the resolution.

About Sampling Points AUTO

Sampling points or sampling interval is automatically set according to the sweep span and
wavelength resolution setting.
The sampling intervals that do not cause UNCAL vary depending on the resolution setting.
For example, to prevent UNCAL from occurring at a resolution of 0.05 nm, the sampling interval
must be 0.002 nm or less. To measure at 20 nm sweep span, the sample points must be set at
least to 20 ÷ 0.002 + 1 = 10001. For details, see “Number of samples (Sampling Points)” in section

1.1.

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2.4 Measurement Sensitivity

Procedure

1.

Press SETUP. The Setup menu appears.

2.

Tap Sensitivity. The Sensitivity menu appears.

3.

Tap Sensitivity Mode to set the sensitivity mode to RAPID or TRAD.

For the next step, see the following pages.

2

Setting the Measurement Conditions

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2.4 Measurement Sensitivity

Settings in RAPID mode

Carry out the following steps if you selected RAPID in steps 3.

4.

Tap Sensitivity Select. A RAPID selection menu and SENSITIVITY setting window are

displayed.

(If you selected RAPID in step 3, instead of using the SETUP key, you can press

windows.)

You can set the value by either of the following methods.

Selecting by tapping the menu

5.

Tap RAPID1, RAPID2, RAPID3, RAPID4, RAPID5, or RAPID6 to select the

measurement sensitivity (sweep speed). The measurement sensitivity corresponding to
the selected value appears in the Sensitivity Level menu.

Selecting on the SENSITIVITY setting window

5.

On the SENSITIVITY setting window displayed in step 4, tap – or +. The highlighted

value (RAPID1 to RAPID6) changes every time you tap.

6.

When the sweep speed (measurement sensitivity) you want to use is highlighted, tap

Exit. The measurement sensitivity corresponding to the selected RAPID value appears in
the Sensitivity Level menu.

to display the same

SENS

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2.4 Measurement Sensitivity

Settings in TRAD mode

Carry out the following steps if you selected TRAD in steps 3.

4.

Tap Sensitivity Select. A TRAD selection menu and SENSITIVITY setting window are

displayed.

(If you selected TRAD in step 3, instead of using the SETUP key, you can press

windows.)

You can set the value by either of the following methods.

Selecting by tapping the menu

5.

Tap More 1/2 and More 2/2 to view the available values in the menus. Tap the sweep

speed (measurement sensitivity) you want to use. The measurement sensitivity
corresponding to the selected value appears in the Sensitivity Level menu.

More 1/2 menu: N/HOLD, N/AUTO(x2), N/AUTO, NORMAL(x2), NORMAL, MID(x2), MID
More 2/2 menu: HIGH1(x2), HIGH1, HIGH2(x2), HIGH2, HIGH3(x2), HIGH3

Selecting on the SENSITIVITY setting window

5.

On the SENSITIVITY setting window displayed in step 4, tap – or +. On the More 1/2 and

More 2/2 menus, the highlighted value changes every time you tap.

to display the same

SENS

2

Setting the Measurement Conditions

6.

When the sweep speed (measurement sensitivity) you want to use is highlighted, tap

Return. The measurement sensitivity corresponding to the selected TRAD value appears
in the Sensitivity Level menu.

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2.4 Measurement Sensitivity

Setting the measurement sensitivity by entering the measurement
level directly

3.

Tap Sensitivity Level. The SENS LEVEL setting window appears.

4.

Enter the approximate minimum power value you want to measure in the displayed window.

For instructions on how to select items and how to set values, see chapter 4 in the Getting Started

Guide.

5.

Tap Return.

Note

• The assigned value is applied to the measurement conditions area.

• When a setting is changed,

appears in the measurement condition area.

Setting CHOP MODE

3.

Tap Chop Mode to select Off or SWITCH.

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Note

When CHOP MODE is set to SWITCH, “/SW” is added in the corresponding sensitivity menu.

RAPID mode: RAPID4/SW, RAPID5/SW, RAPID6/SW
TRAD mode: MID(x2)/SW, MID/SW, HIGH1(x2)/SW, HIGH1/SW, HIGH2(x2)/SW, HIGH2/SW,

HIGH3(x2)/SW, HIGH3/SW

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2.4 Measurement Sensitivity

Explanation

Measurement Sensitivity

There are two measurement sensitivity modes: RAPID and TRAD. The operation mode of the
analog amplifier circuit built into the instrument is set according to the measurement sensitivity
setting.

RAPID mode

This sensitivity mode is specialized for high-speed measurement of CW light. Select from the
following:

RAPID1, RAPID2, RAPID3, RAPID4, RAPID5, RAPID6

TRAD mode

This sensitivity mode can measure both CW light and pulse light. It operates in the same way
as the conventional sensitivity mode of YOKOGAWA’s optical spectrum analyzers. Select from
the following:

N/HOLD, N/AUTO, NORMAL, MID, HIGH1, HIGH2, HIGH3

Rapid mode
N/AUTO(x2), NORMAL(x2), MID(x2), HIGH1(x2), HIGH2(x2), HIGH3(x2)

2

Setting the Measurement Conditions

• If you select N/HOLD, the analog amplifier circuit is set to fixed gain mode. The gain is set
according to the reference level set in section 2.5. If the gain is fixed, the measurement
range is from “reference level – 20 dBm” to “reference level + 10 dBm” due to the limited
effective measurement range.

• If you select a setting other than N/HOLD, the analog amplifier circuit is set to auto gain
mode. This mode allows a wider range of levels to be measured in a single sweep.

• For settings other than N/HOLD, you can select double speed mode, which measures at
a sweep speed that is about twice as fast as usual. “(x2)” is appended to the sensitivity
setting name such as NORMAL(x2) and MID(x2).

• The double speed mode is suitable for measuring light sources, such as LED light sources,
where the level change of the spectral shape is relatively gradual.
This mode has the following features.

• The noise level is approximately 2 dB higher than normal.

• If used under UNCAL conditions, for waveforms that have sharp spectral shape
changes, such as those produced by the DFB-LD, the level and wavelength
measurement accuracies may degrade. First check the measurement spectrum, and
then select this value if appropriate.

Measurement sensitivity by entering the measurement level
directly

Enter the approximate minimum power value you want to measure as the measurement sensitivity
value, and the sensitivity mode will be set automatically.

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Waveform when CHOP MODE is Off

Waveform when CHOP MODE is SWITCH

2.4 Measurement Sensitivity

CHOP mode

When the CHOP mode is set to SWITCH, measurements are made while reducing the stray light
in the monochromator, which is generated according to the intensity of the input light power. The
measurement time is doubled, but a wide dynamic range can be measured.
You can set SWITCH when the following measurement sensitivity is selected.

RAPID mode: RAPID4, RAPID5, RAPID6
TRAD mode: MID(x2), MID, HIGH1(x2), HIGH1, HIGH2(x2), HIGH2, HIGH3(x2), HIGH3

CHOP mode feature

CHOP mode Features Advantages Disadvantages

Off The stray light component is

also measured.

Measurement is fast
even for high-sensitivity
measurements.

Since the stray light component
is also measured, low level
components are inaccurate
when the power of the light
source is high.

SWITCH Two sweeps are made in one

measurement. Only the stray
light component is measured
in the first sweep, and high
dynamic measurement is
possible by subtraction.

Stray light suppression ratio:
80 dB (Typ.) or more

A measurement can
be made in a short
time with the stray light
removed.

If the measurement time is long,
the measurement is affected by
variation in the measured light
source over time.

Monochromator stray light

The instrument has a newly designed, high-performance monochromator. Depending on the
measurement conditions, stray light at a level 60 dB to 70 dB below the spectral peak level, as
well as other stray light specific to the monochromator may appear in wavelength areas 100 nm
to 200 nm from the peak wavelength. If these stray lights have severe impact on measurements,
you can set the sensitivity to MID or HIGH 1-3 and set CHOP MODE to SWITCH in order to reduce
their effects.

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2.5 Level scale

When measurement waveforms are displayed, the level scale is displayed with absolute values. The
level scale with absolute values is the main scale and that with relative values the sub scale. For a
description of the sub scale, see section 2.6.

Procedure

Configuring the level scale with absolute values (main scale)

1.

Press LEVEL. The Level menu appears.

Changing to the log scale display

2.

Tap Log Scale. The vertical scale is displayed with the currently set log scale value. At

the same time, the LOG SCALE setting window appears.

3.

Enter the log scale value in the displayed window.

For instructions on how to select items and how to set values, see chapter 4 in the

Getting Started Guide.

2

Setting the Measurement Conditions

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2.5 Level Scale

Changing to the linear scale display

2.

3.

4.

For instructions on how to select items and how to set values, see chapter 4 in the

Tap Linear Scale. The vertical scale is displayed with the currently set linear scale value.

Tap Linear Base Level. The BASE LEVEL setting window appears.

Enter the value at the bottom of the scale in the displayed window.

Getting Started Guide.

Setting the vertical scale unit

2.

Tap Level Unit. The vertical scale unit is changed.

The units that you can select vary depending on the specified horizontal scale unit,
vertical scale, and reference level unit.

Horizontal Scale Log/Linear Scale Reference Level Level Unit

nm Log Scale — dBm, dBm/nm
Linear Scale pW pW, pW/nm
nW nW, nW/nm
µW µW, µW/nm
mW mW, mW/nm
THz Log Scale — dBm, dBm/THz
Linear Scale pW pW, pW/THz
nW nW, nW/THz
µW µW, µW/THz
mW mW, mW/THz

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2.5 Level Scale

Setting the number of divisions in the vertical scale (only for log scale)

2.

Tap Log Scale.

3.

Tap More 1/2. The More 2/2 menu appears.

4.

Tap Y Scale Setting. The Y Scale Setting menu appears.

5.

Tap Y Scale Division. A menu appears for selecting the number of divisions.

6.

Tap 8 or 10. The vertical scale is displayed with the specified number of divisions.

For linear scale, the number of divisions is fixed at 10.

2

Setting the Measurement Conditions

Setting the reference level position on the screen (for log scale)

5.

Continuing from step 4 in “Setting the number of divisions in the vertical scale,” tap Ref

Level Position. A window appears for setting the reference level position on the screen

(REF position).

6.

Enter the number of divisions counted from the bottom of the waveform display area.

For instructions on how to select items and how to set values, see chapter 4 in the

Getting Started Guide.

• If the REF position value is greater than the number of divisions, it is reduced to the same value
as the number of divisions.

• For linear scale, the REF position is fixed at the top (fixed at 10 DIV).

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2.5 Level Scale

Setting the reference level

There are three ways to set the reference level.

• Using the Reference Level parameter

• Using the one-action keys

• Setting the reference level to the moving marker level

1.

Press LEVEL. The Level menu appears.

Using the Reference Level parameter (log scale)

2. If the vertical scale is not set to log scale, tap
proceed to step 3.

3. Tap

4. Enter the reference level in the displayed window.

For instructions on how to select items and how to set values, see chapter 4 in the

Reference Level

Getting Started Guide.

. The REF LEVEL setting window appears.

Log Scale

. If the log scale is displayed,

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Note

The vertical scale setting is applied to the waveform display in real-time.

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Using the Reference Level parameter (linear scale)

2.5 Level Scale

2. If the vertical scale is not set to linear scale, tap
displayed, proceed to step 3.

3. Tap

4. Enter the reference level in the displayed window. When you enter a value, a menu

5. On the unit selection menu, tap the unit you want to use. The reference level will be set.

Reference Level

appears for selecting the unit.

. The REF LEVEL setting window appears.

Linear Scale

. If the linear scale is

2

Setting the Measurement Conditions

Note

If you enter the value using the rotary knob or by tapping – and + on the setting window, the reference
level will be set in the current unit.

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2.5 Level Scale

Setting using one-action

2.

Tap Peak Level -> Ref Level:

Tap Auto Ref Level Off On to select On:

Tap one of the following two menus.

The reference level is set to the peak level of the active trace waveform. The specified reference

level is displayed, and the displayed waveform is redrawn according to the new reference level.

For each sweep, the reference level is set to the peak level of the active trace waveform.

• This does not work when the active trace is set to a type other than Write (Max Hold, Min Hold,
Calculate, Roll Average).

• If this soft key is on,

at the bottom of the screen will be highlighted.

Set to the peak level value

Automatically set to the peak level
for each sweep

Setting the reference level to the moving marker level

1.

Press MARKER. The Marker menu appears.

2.

With the moving marker (see section 5.1) displayed, tap Marker -> Ref Level. The

specified reference level is displayed, and the displayed waveform is redrawn according
to the new reference level.

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Explanation

Level scale with absolute values (main scale)

Log Scale **.*dB/D

This soft key switches the vertical scale to log display and sets the scale.
You can set the value between 0.1 and 10.0 dB/DIV. You can set it in steps of 0.1 dB. When

COARSE is selected, you can set it in steps of 1-2-5 (e.g., 1 dB/DIV → 2 dB/DIV → 5 dB/DIV).

When you change this setting, the displayed waveform is redrawn according to the new scale.
If you specify a scale greater than 5 dB/DIV in fixed range mode (measurement sensitivity N/
HOLD), a warning will be displayed because the top and bottom of the waveform will not be
measured correctly.

Measurement sensitivity and effective vertical scale range

If the measurement sensitivity is set to N/HOLD, the internal amplifier is set to fixed gain. The
gain is set automatically from the five available settings depending on the reference level (REF)
setting. The effective range of measurement data is limited to the following range relative to
the reference (REF) level.

2.5 Level Scale

2

Setting the Measurement Conditions

REF−20 dBm < (effective range) < REF+10 dBm

If the scale is set to 10 dB/DIV, the display will fall outside the effective range, and thus
10 dB from the top edge of the screen and 20 dB from the bottom edge of the screen will be
inaccurate.
If the measurement sensitivity is set to N/HOLD, we recommend that you use the level scale
at 5 dB/DIV or less.
If the measurement sensitivity is N/AUTO, MID, or HIGH 1 to 3, auto gain is used allowing a
wide level range to be measured in one sweep. Select the appropriate sensitivity according to
the reception level necessary for measurement.

Linear Scale

This soft key sets the scale to linear scale.
Set the scale per division using the reference level.

Linear Base Level **.*mW

This soft key is used to set the value at the bottom of the scale when the vertical scale is set
to linear scale. This soft key is disabled when the vertical scale is set to log scale.
You can set the value between 0.0 and REF level × 0.9. You can set it in steps of 0.1. When
COARSE is selected, you can set it in steps of 1. You can set the same unit as the reference
level unit.
When you change this setting, the displayed waveform is redrawn according to the new scale.

The scale display at the upper left of the waveform is set to 1/10 of [reference (ref) level −

bottom (Base) level (*W/D).
For details on the reference level setting, see the explanation provided later.

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2.5 Level Scale

Level Unit dBm dBm/nm

This soft key sets the display to dBm or dBm/nm when the vertical scale is set to log scale.

dBm: Power per resolution (absolute power)

dBm/nm: Power per nm (power spectral density)
For details on how to use dBm and dBm/nm, see “Power spectral density display” in “Features.”
If you set a calculated waveform to power spectral density, the level unit is automatically set to
dBm. If power spectral density is assigned as the calculated waveform to Trace F and the unit
is set to dBm/nm, Trace F enters FIX mode, and the waveform is no longer updated.

Level Unit mW mW/nm

When the vertical scale is set to linear scale, this soft key switches the display between nW,

μW, mW, or pW (absolute power), and nW/nm, μW/nm, mW/nm or pW/nm (power spectral

density).

Reference level

Log scale (Reference Level)

You can set the reference level of the log scale between –90.0 and 30.0 dBm. You can set it in
steps of 0.1. When COARSE is selected, you can set it in steps of 1.

Linear scale (Reference Level)

You can set the reference level of the linear scale between 1.00 pW and 1000 mW.
When 1.00 to 9.99 (pW, nW, µW, mW) is selected, you can set it in steps of 0.01.
When 10.0 to 99.9 (pW, nW, µW, mW) is selected, you can set it in steps of 0.1.
When 100 to 999 (pW, nW, µW, mW) is selected, you can set it in steps of 1.

When COARSE is selected, you can set it in steps of 1-2-5 (e.g., 1pW → 2pW → 5pW →

10pW → 20pW).

The unit will change if you change the value in the following manner: 999 → 1.00 or 1.00 →

999.

(Example: pW → nW or nW → pW)

One-action keys

This is a general term for the keys that use data from the active trace waveform to set
measurement conditions.
To use them, a waveform must be displayed in the active trace.

• Peak Level -> Ref Level

The reference level is set to the peak level of the active trace waveform.

The specified reference level (peak level value) is displayed in a reference level setting

window. Then, you can further change the reference level.

On the log scale, you can change the value between –90.0 dBm and +30.0 dBm.

On the linear scale, you can change the value between 1.00 pW and 1000 mW.

If the peak level value exceeds the allowed range, it is set to the nearest value within the

range and a warning is displayed.

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2.5 Level Scale

Moving marker

Marker -> Ref Level

The reference level is set to the level of the moving marker placed on the measured waveform.
The specified reference level and waveform are displayed in a reference level setting window.
Then, you can further change the reference level.
On the log scale, you can change the value between –90.0 dBm and +30.0 dBm.
On the linear scale, you can change the value between 1.00 pW and 1000 mW.

If the moving marker value exceeds the allowed range (the moving marker is at a point
where the level is –210 dBm), it is set to the nearest value within the range and a warning is
displayed.
In the following states, the Marker -> Ref Level key is disabled.

• When the moving marker is off (Marker Active is OFF)

Main Scale Initialize

This function returns only the level scale (main scale of the vertical scale) to its original
condition after the waveform is moved or zoomed through dragging or pinching out or pinching
in. This is not synchronized to the sub scale display.

2

Setting the Measurement Conditions

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2.6 Sub Scale

The level scale is displayed based on relative values when a differential waveform (based on LOG
values) or normalized waveform is displayed. The sub scale is the level scale with relative values. For
details on the level scale with absolute values (main scale), see section 2.5.

Procedure

Displaying the sub scale

Follow the procedure in sections 4.5 or 4.6 to display differential waveforms or normalized
waveforms.

Auto scaling the sub scale

1. Press LEVEL. The Level menu appears.

2.

Tap More to display the More 2/3 menu.

3. Tap Auto Sub Scale Off On to select On or Off.

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2.6 Sub Scale

Log display of the sub scale

3.

Tap Sub Log. The sub scale is displayed with the currently set log scale value. At the same

time, the SUB SCALE LOG setting window appears.

4.

Enter the log scale value in the displayed window.

For instructions on how to select items and values, see chapter 4 in the Getting Started Guide.

Setting the offset

3.

Tap Offset Level. An offset value setting window appears.

4.

Enter the offset value in the displayed window.

For instructions on how to select items and values, see chapter 4 in the Getting Started Guide.

2

Setting the Measurement Conditions

Setting the REF position

2.

Tap More to display the More 3/3 menu.

3.

Tap Y Scale Setting. The Y Scale Setting menu appears.

4.

Tap Sub Ref level Position. The REF POSITION setting window appears.

5.

Enter the REF position in the displayed window.

For instructions on how to select items and values, see chapter 4 in the Getting Started Guide.

6.

Tap Return.

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