Agilent 71450B User Guide

User's Guide

HP

Optical Spectrum

Analyzers

71450B/1B/2B

HP Part No. 70950-90049

Edition 1

Printed in USA June 1995

1400 Fountaingrove Parkway,

Santa Rosa, CA

95403-1799, USA

Notice.

The information contained in this document is subject to change

without notice. Hewlett-Packard makes no warranty of any kind with regard

ackard

this

of

shall

material,

this

to

merchantability

be liable

not

damages

for

connection

in

including

tness

and

contained

errors

with

but

for

the

limited

not

particular

a

herein

furnishing,

the

,

to

purpose

incidental

for

or

performance

implied

Hewlett-P

.

warranties

consequential

or

use

or

,

material.

.

.S

U

the

Restricted

Rights

Government

Rights

the

of

252.227-7013

Commercial

agencies

other

Legend.

subject

is

echnical

T

in

DOD

for

Computer

.

Use

restrictions

to

Data

agencies

Software

duplication,

,

set

as

and Computer

subparagraphs

and

,

Restricted

or

forth

Software

Rights

disclosure

in

clause

by

subparagraph

at

and

FAR

at

(c)

clause

(c) (1)

(1)

(c)

ARS

DF

the

of

(2)

52.227-19

(ii)

for

c



Copyright Hewlett-P

ackard Company 1995

written permission is prohibited, except as allowed under the copyright laws.

WARNING

Light energy can radiate from the front-panel

MONOCHROMATOR OUTPUT

connector on HP 71451B instruments (HP 70951B modules). The light

emitted from this connector is the ltered and slightly attenuated

light input to the front-panel

MONOCHROMATOR OUTPUT

MONOCHROMATOR INPUT

connector. The

connector radiates light energy in the following

instrument modes: preselector, stimulus response, and photodetector test.

N

O

I

T

U

A

C

N

O

I

T

U

A

C

ON

I

T

U

A

C

Condensation degrades the optical spectrum analyzer's performance. Always

cause

may

protect the

optical spectrum

condensation. A

environment to

power

input

otal

T

exceed

not

must

instrument.

instruments

compression

Electrostatic

connectors

momentarily

void

A

the

of

The

is

discharge

Therefore

.

short

touching

instrument.

earth-grounded

void moving

awarm

the

to

dBm.

+30

maximum

dBm.

+20

dBm.

+10

(ESD)

before

,

center

the

rear-panel

the

sure

Be

prevent

to

analyzer from

the optical

environment.

front-panel

in

ower

P

photodetector

safe

largest

The

damage

can

connecting any

outer

and

connectors

the

that

buildup

of

conditions

spectrum analyzer

MONOCHROMATOR

+30

excess

of

input

measurable

circuits associated

cable to

conductors

without

static

spectrum

charge

optical

that

INPUT

dBm

level

power

of

rst

analyzer

.

from

connector

may

on

level

with

rear-panel

a

cable

the

touching

cold

a

damage the

71451B

HP

before

signal

rear-panel

connector

together

frame

the

properly

is

.

,

iii

Optical Spectrum Analysis with the HP

71450B/1B/2B

Be sure to read this introduction for your optical spectrum analyzer.It

introduces you to many of the optical spectrum analyzer's features. The

optical spectrum analyzer displays the optical power of the input light spectra

as a function of wavelength.

Missing graticules

is

This

.

graticule

the

show

not

do

In this

done to

book, man

make it

gures

y

easier

spectrum

optical

the

of

important

see

to

details.

analyzer's

screen

iv

Accurate measurements require clean connections

When connecting ber-optic cables, do the following steps:

1. Clean the connectors as described in Chapter 1. Dry connections are recommended.

2. Align the connectors so that the ber end does not touch the outside of the mating connector.

Do not rub the ber end against any other surfaces.

3. After the ferrule is properly seated inside the connector, use one hand to keep it straight and

nger-tighten it with the other hand.

Automatic

ensures

accuracy

alignment

amplitude

Refer

undertightening

ensure the

o

T

analyzer's

should

that

Moved.



Subjected



armed

W



manufacturer's

the

to

connectors

maximum

4

ALIGN

UTO

A

be performed

environmental

large

to

start

the

at

up

data

can

amplitude

feature

5

whenever

of

sheet

in

result

accuracy

. This

each day

recommendations.

torque

for

misalignment

use

,

automatic

an

is

optical

the

temperature

.

nonrepeatable

and

the

spectrum

changes

Overtightening

connections.

optical

spectrum

alignment

analyzer

.

or

procedure

been:

has

Refer to Chapter 1 for information on aligning and calibrating the optical

spectrum analyzer.

v

Softkeys select

instrument features

You control the optical spectrum analyzer using softkey menus. Softkeys are

the seven buttons located on each side of the screen. Left-side softkeys select

main menus. Right-side softkeys present instrument features. Right-side

softkeys are often displayed in several

pages

.

Changing measurement

parameters is easy

Use the front-panel knob, step keys, or numeric keypad to enter new

measurements settings.For example, press the

4

CENTER

5

key to change

the displayed center wavelength. After changing the setting, pressing the

4

5

key disables the keypad, knob, and step keys until another function is

HOLD

selected. Pressing the

4

5

Use the

When

backspace

(backspace)



pressed,

over

the

numbers

4

HOLD

key

5

key twice blanks the right-side softkeys.

speed

to

softkey

using

your

menu

the

navigation

displayed.

is

data-entry

through

Also,

keypad.

softkey

use

this

menus

key

vi

.

to

Keys in this manual

4

5

letters indicate normal front-panel keys. Most of these functions also can be performed using

boxed

ys.

softke

N

NN

N

shadow

letters indicate

spectrum analyzer

Optical

ys.

softke

Menu

Selections.

vii

Automatically locate

and display signals

Press the front-panel

4

AUTO MEAS

5

key automatically to locate and display the

largest input signal. The optical spectrum analyzer zooms to the signal by

changing the displayed center wavelength, span, and reference level values.

viii

Characterize signals

with the press of a

button

Three advanced-measurement programs automatically characterize LEDs, DFB

lasers, and Fabry-Perot lasers. Press the front-panel

invoke these programs.You can design your own programs (also known as

downloadable programs) using the information supplied in the

Guide

.

4

USER

5

key to nd and

Programmer's

Characterization

of Fabry-P

erot Laser

ix

Insrument modes

increase capability

Depending on the model number, up to six separate operating modes are

available:



Optical spectrum analyzer. Refer to Chapter 1



Stimulus-response measurement. Refer to Chapter 5.



Fast pulse measurement. Refer to Chapter 5.



Power meter. Refer to Chapter 5.



Preselector. Refer to Chapter 5.



Photodiode responsivity measurement. Refer to Chapter 5.

(HP 71451B only)

(HP 71451B

only)

markers

Use

values

measure

to

Trace

position

any

Markers

markers

and

allow

on

peak

trace

the

searches

you

swiftly

ou

Y

.

are

measure

to

even

can

discussed

the

compare

Chapter

in

wavelength

positions

9.

and

on

amplitude

separate

of

traces

.

x

View three-dimensional

display

The optical spectrum analyzer oers considerable trace control. This includes

a three-dimensional view that provides a graphic history of a response. Refer

to Chapter 8 for information on viewing three-dimensional displays.

xi

Limit lines enhance

production-line testing

With the optical spectrum analyzer's limit-line feature, you can display a set

of custom lines that describe the acceptable limits of a displayed response.

Repeatable comparisons can then be made with

PASS

and

FAIL

conditions

automatically displayed on the screen.

Saving

setups

instrument

you

saves

time

repeatedly

you

If

save

to

sure

be

be recalled

can

automatically

Chapter 2.

xii

congure

the

any

at

. Saving

settings

time

and

optical

the

measurement

a

as

congure

to

recalling

spectrum

state

optical

the

measurement

analyzer

Measurement

.

spectrum

states

the

to

described

is

same

states

analyzer

settings

in

,

Use the custom keypad

for swift measurements

The optical spectrum analyzer comes with a custom keypad that snaps into

the front panel of HP 70004A displays. The keypad gives you quick access to

common instrument functions. (Each of these functions can also be accessed

using the normal softkey menus.)

If you have the custom keypad, practice using it. You'll nd that the time

required for many of the procedures in this book will be signicantly reduced.

If you need to remove the custom keypad, simply push the small button

located on the keypad's right side.

xiii

Screen annotation

provides valuable

information

Annotation displayed on the screen shows you the current measurement

window. This includes displayed wavelength, sensitivity, and sweep time.

The display's active function area shows the value of any function that

has been activated for change. In the following gure, the active function

annotation indicates that the displayed wavelength span has been selected for

change.You may change its value using the knob, keypad, or step keys.You

may also press a softkey to select another active function.

TheSdisplayed at the bottom of the screen shows that the optical spectrum

analyzer is using sample detection. If theSis missing, peak detection is used.

xiv

Warranty

This Hewlett-Packard instrument product is warranted against defects in

material and workmanship for a period of one year from date of shipment.

During the warranty period, Hewlett-Packard Company will, at its option,

either repair or replace products which prove to be defective.

For warranty service or repair, this product must be returned to a service

facility designated by Hewlett-Packard. Buyer shall prepay shipping charges

to Hewlett-Packard and Hewlett-Packard shall pay shipping charges to return

duties

product

the

and taxes

Buyer

to

for products

However

.

returned to

shall

Buyer

,

Hewlett-Packard

pay

shipping

all

from

charges

another

,

country

.

,

Hewlett-Packard

Hewlett-P

instructions

does

rmware

Limit

The

or

ackard

when

warrant

not

be

will

of

tion

a

foregoing

inadequate

interfacing,

environmental

maintenance

or

NO

OTHER

W

warrants that

for use

with an

properly installed

the

that

uninterrupted

arranty

W

warranty

maintenance

unauthorized

specications

.

ARRANTY

its software

instrument

operation

error-free

or

not

shall

Buyer

by

modication

the

for

EXPRESSED

IS

and rmware

will

on that

of

instrument.

instrument,

the

.

defects

to

apply

Buyer-supplied

,

misuse

or

product,

OR

execute

resulting

operation

,

improper

or

IMPLIED

designated

programming

its

Hewlett-P

software

or

from

software

site

HEWLETT-P

.

by

ackard

or

,

improper

or

outside

preparation

A

of

CKARD

SPECIFICALLY DISCLAIMS THE IMPLIED WARRANTIES OF

MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

Exclusive Remedies

THE REMEDIES PROVIDED HEREIN ARE BUYER'S SOLE AND EXCLUSIVE

ANY

HEWLETT-P

REMEDIES

DIRECT

AMA

D

.

INDIRECT

,

GES

WHETHER

LEGAL THEORY

,

.

CKARD

A

SPECIAL,

ASED

B

SHALL

INCIDENT

CONTRACT

ON

BE LIABLE

NOT

OR CONSEQUENTIAL

AL,

TORT

,

FOR

OTHER

ANY

OR

,

the

xv

Certication

Hewlett-Packard Company certies that this product met its published

specications at the time of shipment from the factory. Hewlett-Packard

further certies that its calibration measurements are traceable to the United

States National Institute of Standards and Technology, to the extent allowed

by the Institute's calibration facility, and to the calibration facilities of other

International Standards Organization members.

xvi

Assistance

Product maintenance agreements and other customer assistance agreements

are available for Hewlett-Packard products.

For any assistance, contact your nearest Hewlett-Packard Sales and Service

Oce.

xvii

CAUTION

N

I

N

R

A

W

Safety Symbols

The following safety symbols are used throughout the manual set. Familiarize

yourself with each of the symbols and its meaning before operating this

instrument.

The

caution

sign denotes a hazard. It calls attention to a procedure which,

if not correctly performed or adhered to, could result in damage to or

destruction of the instrument. Do not proceed beyond a

caution

sign until

the indicated conditions are fully understood and met.

procedure

attention

calls

and

It

adhered

or

warning

a

met.

to

,

sign

hazard.

denotes

not

.

are

Do

sign

correctly

proceed

not

understood

fully

warning

G

The

which,

of

loss

if

life

conditions

a

performed

beyond

to a

could result

until the

in injury

indicated

or

xviii

Contents

1. Displaying Signals (Part 1)

Setting Wavelength and Reference Level . . . . . . . .

To view a signal using markers . . . . . . . . . . .

To return to full span . . . . . . . . . . . . . . .

To allow extended wavelength range . . . . . . . . .

Tochange the reference level . . . . . . . . . . . .

Tochange the reference position . . . . . . . . . . .

view the

To

hange

c

o

T

oset

o

T

o

T

o

T

Sensitivit

increase

disable

Setting

Automatically

view

o

T

automeasure

o

T

automeasure

o

T

automeasure

o

T

automeasure

o

T

Changing

hange the

oc

T

hange the

oc

T

Understanding

amplitude meter

ter

cen

the

annotation

.

y

sensitivit

the

autoranging

uning

T

signal

a

using

at

to

optimizing sensitivit

Amplitude

the

amplitude scale

amplitude units

Multiple-Order

To test for sub-multiples . . . . . . . . . . . . . .

Aligning the Optical Spectrum Analyzer . . . . . . . .

To align at largest input signal . . . . . . . . . . .

To align at the marker . . . . . . . . . . . . . . .

To align with Option 002 internal light source . . . . .

external

an

with

align

o

T

alignmen

ve

remo

o

T

Calibrating the

To calibrate w

To calibrate po

Optical Spectrum Analyzer .

avelength . . . . . . . . . . . . . .

wer and w

To turn o user-calibration .

To erase user-calibration

Cleaning Connections

.

. .

.

scale

elength

v

a

Units .

. .

onses .

.

size .

. .

.

y .

.

. .

.

. .

.

. .

.

elength step

av

w

readouts

.

y

.

Signals

to

automeasure

ecied

sp

a

ecied

sp

a

ecied

sp

a

Scale and

ligh

osets

t

.

el

lev

.

Resp

t source

.

span

log

w

.

avelength . . . . . . . . .

. . . . . . . . . . .

.

. . . . . . . . . . . . . .

for Accurate Measuremen

.

. .

.

. .

.

. .

.

. . . . . .

ts . . . .

1-4

1-10

1-11

.

1-12

.

1-12

.

1-14

.

1-15

.

1-15

.

1-16

.

1-17

.

1-17

.

1-18

.

1-18

.

1-19

.

1-20

.

1-21

.

1-21

.

1-22

.

1-26

1-28

1-29

1-30

.

1-31

.

1-32

1-35

1-37

1-40

1-41

1-42

Contents-1

To clean a non-lensed connector . . . . . . . . . . .

To clean an adapter . . . . . . . . . . . . . . . . . . 1-45

To test insertion loss . . . . . . . . . . . . . . . .

To test return loss . . . . . . . . . . . . . . . . .

2. Displaying Signals (Part 2)

Resolving Wavelengths . . . . . . . . . . . . . . . .

To resolve closely spaced signals . . . . . . . . . . .

Tochange the RB/span ratio . . . . . . . . . . . .

Reducing Displayed Noise . . . . . . . . . . . . . .

To reduce the displayed noise . . . . . . . . . . . .

Increasing Dynamic Range . . . . . . . . . . . . . .

.

. .

time

.

. .

.

. .

.

eeps

.

. .

.

t

.

state

.

. .

.

range

mode

. .

.

single sw

. .

.

retrace

.

triggering

.

eep

Setups

measuremen

a

chop

Sw

tin

con

sw

the

sw

eeps

Sw

freerun

video

triggering

line

external

the

y

recall

or

e

dynamic

eeps

uous or

eep time

eep

sw

eep

triggering

sw

o increase

T

disable

o

T

trolling

Con

set

o

T

set

o

T

stop

o

T

reduce

o

T

riggering

T

use

o

T

use

o

T

use

o

T

use

o

T

dela

To

Saving

Instrument

sav

To

To protect measurement state les . . . . . . . . . .

To select the p ower-on state . . . . . . . . . . . .

.

. .

.

. .

.

. .

.

1-44

1-45

1-46

2-4

2-6

2-8

2-11

2-12

2-13

.

2-14

.

2-16

.

2-19

.

2-20

.

2-20

.

2-21

.

2-22

.

2-25

.

2-25

.

2-26

.

2-26

.

2-27

.

2-27

.

2-28

3. Displaying Pulsed Light

Synchronizing the Light Source . . . . . . . . . . . .

ADC

on

turn

o

T

ADC

on

turn

o

T

Sync

Using the Gated Sw

Contents-2

hronizing

To sync

To select the trigger t

To use the gated sw

the

hronize the optical spectrum

sync

Optical

ype .

eep F

eep feature

(standard

and

Sp

eature . . . .

instrumen

pulsed

ectrum

curren

Analyzer

. . . . . . . . . . . .

.

. . . . .

.

. .

.

t)

(Option 001)

t

. .

.

analyzer . . . . .

. . . . . . . .

. . . . . .

3-4

3-9

.

3-10

.

3-13

.

3-14

3-15

3-16

3-17

4. Measuring Signals

Characterizing DFB Lasers . . . . . . . . . . . . . .

To characterize a DFB laser .............. 4-9

To show the SMSR mo des . . . . . . . . . . . . .

To show the stop-band . . . . . . . . . . . . . . .

Characterizing Fabry-Perot (FP) Lasers . . . . . . . .

Tocharacterize a Fabry-Perot laser . . . . . . . . .

To showthepower-distribution trace . . . . . . . . .

To show the mo des used in measurements . . . . . .

To select the mo des used in measurements . . . . . .

Characterizing LEDs . . . . . . . . . . . . . . . . .

Tocharacterize an LED . . . . . . . . . . . . . .

. .

.

windo

card

ette

disk

.

trace

w

Programs

t

driv

.

e

.

w

sho

o

T

hange

oc

T

Reinstalling

install

o

T

install

o

T

install

o

T

er-distribution

w

o

p

the

tegration

in

the

anced-Measuremen

Adv

memory

the

from

3.5-inc

a

from

computer

a

from

h

. .

.

4-4

4-10

4-11

4-12

4-17

4-18

4-19

4-20

4-25

.

. .

.

4-25

4-26

.

4-28

.

4-29

.

4-30

.

4-31

.

5.

Changing

erforming

P

haracterize

c

o

T

haracterize

c

o

T

displa

o

T

mak

To

use alternativ

To

Making F

Instrument

Stim

trace

a

y

measuremen

e

ast Pulse

Modes

ulus-Resp

single-output

a

dual-output

a

input

of

ts

trace

e

Measuremen

onse

device

er

w

o

p

linear

a

on

denitions

ts

.

scale

.

ts

.

. .

.

To measure fast pulses . . . . . . . . . . . . . . .

Measuring Broadband Power . . . . . . . . . . . . .

To measure broadband p ower . . . . . . . . . . . .

Preselecting a Light Source . . . . . . . . . . . . . .

To preselect a light source . . . . . . . . . . . . .

.

use a

o

T

Measuring

measure photo

o

T

To displa

output

de

single

Photo

mo

detector Resp

detector

resp

y a trace of input po

cable

onsivit

.

y

.

onsivit

y

wer . . . . . .

.

. .

.

. .

.

. . . .

.

Contents-3

5-4

5-9

5-14

5-16

5-18

5-20

5-21

5-24

5-26

5-29

5-31

5-33

5-37

5-41

6. Using Option 002, Built-in White Light Source

Operating the LightSource . . . . . . . . . . . . . .

To turn on the light source . . . . . . . . . . . . .

Using the Light Source with the HP 71451B . . . . . .

Stimulus-Response Measurements with the HP 71450B/2B

To characterize a single-output device . . . . . . . . . . 6-10

Tocharacterize a dual-output device . . . . . . . . .

To display a trace of input power . . . . . . . . . .

Tomake measurements on a linear scale . . . . . . .

To use alternative trace denitions . . . . . . . . . .

Replacing the Lamp . . . . . . . . . . . . . . . . .

To replace the lamp . . . . . . . . . . . . . . . .

6-4

6-5

6-6

6-15

6-17

6-19

6-21

6-22

Measuring

7.

Characterizing

Preferred

Simplied

T

Characterizing

T

Controlling

8.

Displaying

To

T

measure

o

measure

o

displa

blank

o

observ

o

exc

o

Swept

test

Traces

races

T

y

a

e

hange

Polarization

Optical-to-Optical

(EXT

setup

(INT

setup

test

.

PDL

.

Optical-to-Electrical

.

. .

signal .

PDL

trace

a

trace

a drifting

trace data

Dependent Loss

Devices

detector) .

photo

detector) .

photo

.

. .

.

. .

.

Devices

.

. .

.

. .

.

Toinvoke default trace settings . . . . . . . . . . .

Viewing Three-Dimensional Displa ys . . . . . . . . . .

To view the three-dimensional display . . . . . . . .

Reducing Noise with Video Averaging . . . . . . . . .

To reduce displayed noise . . . . . . . . . . . . . .

Displa

Setting

ying

.

line

y

displa

the

use

o

T

Threshold

race

T

the

y

Displa

eable

v

Mo

a

To set the trace threshold

Simulating an Analog Display .

Tosim

Comparing T

To compare responses

ulate an analog displa

races with T

race Math

. . . . . . . . .

Line

.

. .

y.

.

. .

.

. .

.

. . . . . . . . . . .

. . .

. . . . . . . . .

. .

. . . . . .

.

. .

Changing Trace Length and Interpolation . . . . . . .

. .

.

. . . .

. .

.

. .

.

7-4

.

7-5

.

7-7

.

7-9

.

7-15

7-17

.

8-4

.

8-7

.

8-7

.

8-8

.

8-10

.

8-11

8-12

8-15

8-16

8-17

8-18

.

8-19

.

8-20

.

8-21

8-22

8-23

8-26

8-30

Contents-4

Tochange the trace lengths . . . . . . . . . . . . .

To disable trace A interpolation ......... ... 8-33

Saving and Recalling Traces . . . . . . . . . . . . .

Tosave trace A . . . . . . . . . . . . . . . . . .

To recall trace A . . . . . . . . . . . . . . . . .

9. Using Markers

Selecting and Moving Markers . . . . . . . . . . . .

To displaymarker 1 . . . . . . . . . . . . . . . .

To displaymarkers 2 through 5 . . . . . . . . . . .

Tomoveamarker to the next trace . . . . . . . . .

To turn markers o . . . . . . . . . . . . . . . .

.

hes

Searc

erforming Mark

P

erform a

p

o

T

e

v

mo

o

T

e

v

mo

o

T

hange

c

o

T

Using

T

Changing Mark

Stopping and Pausing the Sweep . . . . . . . . . . .

Measuring Noise Level at Marker . . . . . . . . . . .

Delta

on

turn

o

T

hange

c

o

T

dify

mo

o

T

measure

o

T

om

zo

o

T

a

king

rac

k

trac

To

dene the

To

To select the marker readout type . . . . . . . . . .

Tostopthesweep at the marker . . . . . . . . . .

To pause the sweep at the marker . . . . . . . . . .

measure the

o

T

er

peak

amark

peak

the

Mark

delta

a

elength

v

a

w

ter-frequency

cen

bandwidth

zero-span

to

Drifting

drifting

a

trac

er Readouts

search

ed signal

and pit

.

ers

mark

Signal

signal

king

lev

noise

.

er .

span

.

at

limit

el

. .

cen

to

the

to

denition

. .

.

step

.

mark

.

ter

reference

.

size

.

er

.

screen

.

el

lev

.

. .

.

. .

.

. .

.

. .

.

. .

.

. .

.

8-32

8-34

8-35

9-4

9-7

9-8

9-9

.

9-13

.

9-14

.

9-14

.

9-15

.

9-16

.

9-19

.

9-19

.

9-20

.

9-21

.

9-22

.

9-22

.

9-23

.

9-24

.

9-25

9-26

9-27

9-28

.

Creating

10.

Creating Limit Lines .

ter the limit-lines men

Toen

To create a limit line .

Tomak

To turn on limit testing

To turn on the fail-limit beeper . . . . . . . . . . .

and

Limit

Lines

. . . .

e limit lines relativ

Entering

. . . .

e or xed

. . . . . . . .

Amplitude

. . . . . . . . . . . .

u . .

. . . . . . . . . .

. . . . . . . . . . .

. . .

Corrections

. . . . . .

Contents-5

10-4

10-10

10-12

To blank all traces . . . . . . . . . . . . . . . . .

To erase the limit-line table .... ........ .. 10-13

Saving and Recalling Limit Lines . . . . . . . . . . .

Tosave a limit line . . . . . . . . . . . . . . . .

To list limit-line les in memory . . . . . . . . . . .

To recall a limit line . . . . . . . . . . . . . . . .

Using Amplitude Corrections . . . . . . . . . . . . .

To create amplitude corrections . . . . . . . . . . .

To edit amplitude corrections . . . . . . . . . . . .

To increase the limit-line table size . . . . . . . . .

To turn amplitude corrections on and o . . . . . . .

To erase amplitude corrections . . . . . . . . . . .

. .

.

resp

the

y

rst

the

limit

limit-line

testing

limit

Menu

us

softk

u

that

ey

Lines

onse

limit-line

segmen

table

lines

.

xed

lines

.

to

ey

starts

the

from

.

table

t

.

testing

. .

.

. .

.

user

the

DLP

a

user

.

t

oin

p

.

u

men

.

u

men

11.

utorial:

T

Step

Creating

Designing

cop

To

add a

To

remov

To

Using

1. View

Displa

2.

ter

En

3.

Complete

4.

v

Sa

5.

urn

T

6.

Begin

7.

Mak

8.

User

a

User

men

a

y

softk

a

e

softk

Limit

the

on

Men

To preset the User menu . . . . . . . . . . . . . .

To delete a User menule . . . . . . . . . . . . .

Toenter a small DLP . . . . . . . . . . . . . . .

To edit a small DLP . . . . . . . . . . . . . . . .

Storing and Recalling User Menus . . . . . . . . . . .

.

u

men

User

a

store and

o

T

recall

10-13

10-14

10-16

10-17

10-18

10-21

10-22

10-23

10-24

10-25

.

. .

.

. .

.

10-26

10-27

.

10-28

.

10-29

.

10-30

.

10-31

.

10-32

.

10-33

.

10-35

.

11-4

.

11-9

.

11-9

.

11-10

.

11-11

11-13

11-14

11-15

.

. .

.

Controlling

12.

Controlling Graticules, Annotation, and Titles

Contents-6

Plotting

Annotation,

To place graticules relativ

Printing,

e to 0 dBm

To blank the screen graticule

To blank the screen annotation

To blank the clo c

kdispla

y . . . . .

and

.

. . . . .

. . . . . . .

. . . . . . . .

. . .

. .

. . . . . . .

. . . .

To write a title on the screen . . . . . . . . . . . .

12-4

12-6

12-7

12-8

12-9

To remove a title from the screen . . . . . . . . . .

Controlling the System Clock ........ ...... 12-13

To blank the clo ck display . . . . . . . . . . . . .

To set the clo ck. . . . . . . . . . . . . . . . . .

To select United States or European clock format . . .

Displaying Information About the Instrument. . . . . .

To view the ROM version . . . . . . . . . . . . .

To displaytheinternal state of the instrument . . . .

Printing and Plotting . . . . . . . . . . . . . . . .

To print or plot the display. . . . . . . . . . . . .

Toenter the printer type and address . . . . . . . .

Toenter the plotter type and address . . . . . . . .

or plotting

ting

prin

from

els

lab

ey

softk

t

en

T

. .

.

12-12

12-14

12-15

12-16

12-17

12-18

12-19

12-20

12-21

12-22

12-23

Managing

13.

Selecting

o

T

o

T

o

T

o

T

orking

W

o

T

o

T

o

T

To

To modify le names . . . . . . . . . . . . . . . .

Increasing User Memory . . . . . . . . . . . . . . .

To increase user memory . . . . . . . . . . . . . .

Securing the optical spectrum analyzer . . . . . . . . .

To prevent annotation from displaying . . . . . . . .

o

T

o

T

o

T

Toerasein

To reco

Connecting an External HP-IB Disk Drive

To connect the disk driv

Memory

ormatting

F

and

memory

insert

select

format

c

catalog

sa

recall

cop

erase a

erase all

restrict op

restore op

erase in

a

default

the

memory

card's

hange

a

Files

with

les

all

.

le

a

e

v

.

le

a

ternal

in

y

ver from a full memory erase

memory

.

le

.

les

eration

ternal

ternal memory fully

Memory

card .

memory

.

battery

.

to

4

of

memory

.

4

USER

MENU

partially

e.

.

. .

.

. .

.

. .

.

. .

.

. .

.

. .

.

. .

.

u .

men

5

.

u.

men

5

.

. . . . . . . . . . .

. . . . . . . . .

. . . . . . .

. . . . . . . . . . . . .

.

. .

.

. .

.

. .

.

13-4

.

13-7

.

13-8

.

13-9

.

13-10

.

13-12

.

13-16

.

13-17

.

13-18

.

13-19

.

. .

.

13-19

13-20

13-21

13-23

13-24

13-25

13-28

13-29

13-30

13-34

13-35

. .

.

Contents-7

14. If You Have A Problem

To perform the self-test routine . . . . . . . . . . . .

If operation is erratic .................. 14-5

If displayed color, lines, and text are distorted . . . . .

If advanced-measurement programs are missing . . . . .

If

UNCAL

If

USERCAL

If

ERR 2023

If

ERR 2037

If

ERR 2053

If

ERR 2057

If

ERR 2064

isdisplayed.................. 14-9

is displayed . . . . . . . . . . . . . . . . . 14-10

is displayed ................ 14-11

is displayed ................ 14-12

is displayed ................ 14-13

is displayed ................ 14-15

is displayed ................ 14-17

Glossary

Index

14-4

14-7

14-8

Contents-8

1

Displaying

Signals

(P

art

1)

Displaying Signals (Part 1)

In this chapter, you'll learn how to display optical signals using the following

controls:



Wavelength



Reference level



Sensitivity



Amplitude scale and units

optical

the

.

the

end

of

this

chapter

This chapter

explains how

spectrum analyzer

measurements

ccurate

A

section

a

.

measurements require

describes

and when

. Alignments

making

proper

to align

and

and calibrations

clean connections

ber-optic

connections

calibrate

ensure accurate

At

.

1-2

Displaying Signals (Part 1)

Contents

Setting Wavelength and Reverence Level . . . . . ............... 1-4

To view a signal using markers . . ....................... 1-10

To return to full span .................................. 1-10

To allow extended wavelength range . . . . . . .............. 1-10

To change the reference level .......................... 1-11

To change the reference position ....................... 1-11

To view the amplitude meter . . . . . ...................... 1-11

To change the center wavelength step size . . . . . . . . . ...... 1-12

To oset annotation readouts ........................... 1-12

Setting Sensitivity . . . .................................... 1-14

To increase the sensitivity level ........................ 1-15

1-15

.

disable

o

T

utomatically

A

view a

To

automeasure to

o

T

automeasure to

o

T

automeasure to

o

T

automeasure

o

T

Changing

change

o

T

change

o

T

Understanding

test

o

T

Aligning

align

o

T

align

o

T

align

o

T

To align with an external light source . . . . . .............. 1-30

To remove alignment osets . . . ......................... 1-31

Calibrating the Optical Spectrum Analyzer . . . .............. 1-32

To calibrate wavelength ............................... 1-35

To calibrate power and wavelength . . . .................. 1-37

turn

o

T

erase

o

T

Cleaning

To clean a non-lensed connector . . . . . .

To clean an adapter . . . . . . . .

To test insertion loss

To test return loss

autoranging

Tuning

signal using

optimizing

Amplitude

the

amplitude

the

amplitude

the

Multiple-Order

sub-multiples

for

Optical

the

largest

at

marker

the

at

Option

with

user-calibration

o

user-calibration

Connections

.

Signals

to

automeasure .

a specied

Scale

scale

units

.

Spectrum

signal

input

.

internal

002

.

ccurate

A

for

..........

...........

..

.

span

.

scale

log

.

wavelength

sensitivity .

Units

and

.

Responses

..

.

Analyzer

.

..

.

light

..

.

..

.

Measurements

.........................

........................

.........................

.

..

.

..

.

..

.

..

.

..

.

..

.

..

.

source

.

..................

.

..

.

..

.

..

.

1-16

.

. 1-17

..

.

. 1-17

.

1-18

.

1-18

.

1-19

.

1-20

.

1-21

.

1-21

.

1-22

.

1-26

.

1-28

.

1-29

.

1-29

.

.1-30

..

.

1-40

.

1-41

.

1-42

.

1-44

. . 1-45

1-45

. 1-46

1-3

Setting Wavelength and Reference Level

Displaying signals is as easy as setting the wavelength range, reference level,

and sensitivity. Sweep speed is automatically set by the optical spectrum

analyzer. In fact, the optical spectrum analyzer always uses the fastest sweep

possible while still maintaining a calibrated display.

When the optical spectrum analyzer is rst turned on, the wavelength range

is set to the full 1100 nm span (600 nm to 1700 nm). There is an extended

range that lets you view signals from 350 nm to 2000 nm. However,the

calibrated.

not

is

display

for

signals

within

the

extended

range

1-4

Displaying Signals (Part 1)

Setting Wavelength and Reference Level

The position of the reference level is located on the display by two triangles.

Its position can be changed. The default position is at the ninth major

horizontal graticule line.

Use one of the following three methods to display a signal:



Manually set the wavelength, reference level, and sensitivity.



Use the automeasure routine. (Press



Use markers.

4

AUTO MEAS

5

.)

1-5

Displaying Signals (Part 1)

Setting Wavelength and Reference Level

Waveln and Amptd

menus control

measurement range

Use the Wavelength menu to control the wavelength range. Use the

Amplitude menu to control the reference level and sensitivity. By selecting

the softkeys on these two menus, you can enter the values you need.

After pressing a softkey, it becomes the active function and its value is

displayed in the active function area. Once a function is activated, change its

value using the knob, step keys, or numeric keypad. To discover how easy it

is to adjust the optical spectrum analyzer's settings, connect an input signal,

press the left-side

rotate the front-panel knob and watch the center wavelength change.

NNNNNNNNNNNNNNNNNNNN

Waveln

softkey, then the right-side

NNNNNNNNNNNNNNNNNNNN

CENTER

softkey.Now

1-6

Displaying Signals (Part 1)

Setting Wavelength and Reference Level

Center-wavelength step

sizes can be changed

Osets can be added to

annotation

the

tune

Markers

optical

analyzer

can

spectrum

signal

to

peaks

When center wavelength is the active function, pressing the

485

and

495

keys

steps the center wavelength. The default step size is one tenth of the span.

You can set the size of the steps to a set value. The value you enter does not

depend upon the displayed span.

The Wavelength and Amplitude menus allow you to add osets to all

displayed wavelength and amplitude values. One use of amplitude osets is

to compensate for signal attenuation caused by some devices. Although this

method is fast, it is more accurate to use amplitude correction factors. Refer

to Chapter 10 for a complete discussion of using amplitude correction factors.

reminder

keypad

Custom

,

example

For

In

to

4

STOP

Using

the

of

press

addition

the

set

,

5

the

following

4

NORMAL

the

using

to

wavelength

4

LEVEL

REF

front-panel

gures

ON/OFF

softke

range

,

5

menus,

y

reference

,

4

and

SENS

marker

works

turn

to

5

don't

level,

.

5

keys

for

a

forget

sensitivity

and

you

,

large

marker

corresponding

the

tune

can

signals

and

on

use

.

For

4

CENTER

to

then

front-panel

any

small signals

use

keys.

4

,

5

SP

AN

4

,

5

signal peak.

,you

front-panel

the

ST

5

ART

Step 1

can

,

knob to place the marker on the signal peak. For a more complete discussion

of marker use, refer to Chapter 9.

1-7

Displaying Signals (Part 1)

Setting Wavelength and Reference Level

Press

1.

3. Press

4

SEARCH

PEAK

TO REF LEVEL

.

5

. 4. Press

2.

Press

4

SPAN

4

CENTER

TO

5495495495495

.

5

.

1-8

Displaying Signals (Part 1)

Setting Wavelength and Reference Level

Amplitude meter

measures amplitude of

current trace point

An amplitude meter can be displayed showing the power level of each trace

point as it is acquired. This is particularly useful when monitoring power as

a function of time to observe both long and short term drift. The following

gure shows the amplitude meter displayed on the screen.

Amplitude

meter

showing

power

level

versus

time.

1-9

Displaying Signals (Part 1)

Setting Wavelength and Reference Level

To view a signal using markers

1. Press

4

PEAK SEARCH

5

to activate a marker, and place it on the highest trace

point.

2. If the signal you want to tune to is not the highest peak, rotate the knob to

place the marker at the desired peak.

3. Press

4. Press

5. Press

4

TO CENTER

4

TO REF LEVEL

4

SP

AN

and use

5

,

5

to move the signal to the center wavelength.

5

to move the signal to the reference level.

the knob

,

step

keys

or

,

numeric

keypad

to

reduce

the span.

needed.

6.

T

1.

2.

Press

o

Press

4

SENS

return

the

N

FULL

and

5

to

left-side

N

NN

N

SPAN

full

N

adjust

N

NN

Waveln

N

.

the

span

N

sensitivity

N

softkey

as

.

To allow extended wavelength range

1.

Press

2.

Press

3.

Press the

left-side

the

NNNNNNNNNNNNNNNNNNNNNNNN

MORE 1 of 2

NNNNNNNNN

WL LIM On Off

N

Waveln

NNNNNNNNNNN

.

NNNNNNNNNNNNNNNNNNNNNNNNN

softkey

NNNNNNN

softkey so that

.

NN

NNNNNNNNN

Off

is underlined.

N

NN

N

The displayed wavelength range can now be set from 350 nm to 2000 nm.

However, the extended range is not calibrated.

1-10

To change the reference level

Displaying Signals (Part 1)

Setting Wavelength and Reference Level

1.

Press the left-side

Press

NNNNNNNNNNNNNNNNNNNNNNN

REF LVL

2.

or numeric keypad.

change

o

T

1.

2.

3.

Press

Enter

the

N

MORE

new

a

left-side

N

keypad.

The position

NNNNNNNNNNNNNNNNN

Amptd

softkey.

and enter a new reference level using the knob, step keys,

softkey

N

REF

position

0.0

position

.

N

NN

N

LVL

using

The

10.0.

to

N

POSN

the

N

default

N

.

knob

step

,

position

keys

or

,

9.0.

is

reference

the

N

NN

N

of

1

reference

can be

NN

N

Amptd

N

and

4

from

N

then

level

numeric

To view the amplitude meter

N

1.

Press the left-side

2.

3.

Press

NN

the

N

NN

N

AMETER

N

MORE

N

NNNNNNNNNNNNNNNN

Amptd

N

NN

N

of

1

N

NN

N

NN

Off

On

softkey.

N

NN

N

4

N

so

and

that

NN

MORE

N

NN

N

2

N

NN

N

is

On

N

NN

N

of

softkeys.

4

underlined.

1-11

Displaying Signals (Part 1)

Setting Wavelength and Reference Level

To change the center wavelength step size

1.

Press the

2.

Press the

3.

Press

NNNNNNNNNNNNNNNNNNNN

Waveln

softkey.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

MORE 1 of 2

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

WL STEP AutoMan

softkey.

and use the knob, step keys, or numeric keypad

to enter a new center wavelength step size.

N

NN

Amptd

N

and

4

value

NN

N

Waveln

and then

readouts

N

softkey

N

then

AMP

oset.

the

of

readouts

N

softkey

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

WAVELEN OFFSET

.

N

oset annotation

To

displayed

all

Oset



1.

Press

2.

Press

Enter

3.

Oset

1.

Press

2.

Press

left-side

the

NN

N

all

the

1

MORE

desired

the

displayed

left-side

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

MORE 1 of 2

amplitude

N

of

wavelength

N

.

N

by

N

REF

pressing

N

NN

OFFSET

pressing

by

following

the

N

NN

N

softkeys:

.

the

following

softkeys:

.

3. Enter the desired value of the oset.

1-12

Displaying Signals (Part 1)

Setting Wavelength and Reference Level

1-13

Setting Sensitivity

The sensitivity setting indicates the smallest signal amplitude that will be

displayed across the current wavelength range. Due to instrument tolerances,

the sensitivity's annotation is a nominal value.You can set the sensitivity just

as easily as you would set the reference level. However, increasing sensitivity

slows the sweep speed.

Normally, the optical spectrum analyzer automatically selects the greatest

sensitivity possible that does not require amplication changes during the

desired,

If

. This

and

the

to

video

SENS

you

If

.

sweep

to allow

this change

autoranging

softkey

also

bandwidth

screen

annotation.

manually

be disabled

can

indicates

setting.

increase

in gain.

state

the

autoranging

If

the

This is

using the

autoranging

of

is

sensitivity

known

as

N

NN

N

AUTORNG

asterisk

an

on,

level,

autoranging.

N

NN

N

for

On

a

Off

given

appears

sweep

the

N

softkey

sensitivity

Low

sensitivity

1-14

hides

sidemodes.

Higher

sensitivity

reveals

sidemodes.

Displaying Signals (Part 1)

Setting Sensitivity

The sensitivity indicated for the full span (600 nm to 1700 nm) is around

0

5 dBm. This shows the worst-case condition at 600 nm, which is due to

loss in the internal monochromator. If the stop wavelength is set to less than

900 nm, the sensitivity dramatically improves. This is due to the diraction

grating order used. For complete information on diraction grating orders,

refer to \Understanding Multiple-Order Responses" in this chapter.

To increase the sensitivity level

keys,

the

, step

signal

peak

Press



numeric

Press



at

or

the

,

4

SENS

keypad.

4

REF

top

and

,

5

LEVEL

the

of

enter

and

,

5

screen.

new

a

change

sensitivity

reference

the

level

using

level

the knob

place

to

or

,

or



Press

N

BW,Swp

N

NN

N

,

N

VID

NN

N

BW

N

AutoMan

To disable autoranging

N

1

N

of 4

N

NN

N

NNNNNNNNNNNNNNNNN

Amptd

.

N

NN

N

On

softkey.

NN

N

Off

N

1.

Press the left-side

N

Press

the

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

MORE

N

2.

3.

N

NN

N

AUTORNG

NN

N

softkey

N

NN

N

Off

the

N

is

,

and

so

reduce

that

bandwidth.

video

underlined.

1-15

Automatically Tuning to Signals

The optical spectrum analyzer's

4

AUTO MEAS

5

key automatically locates and

views the largest input signal. Automeasure locates the largest signal in the

full 600 nm to 1700 nm wavelength range, then reduces the span to display

the signal properly. The reference level is set automatically to the signal's

peak and the sensitivity is adjusted as needed.

Using the State menu, you can modify the automeasure routine to perform

one of the following:

locating

Tune



largest

the

End



Optimize



The

order

to

Pressing

wavelength

the

to

input

a predetermined

at

sensitivity.

the

automatic

reduce

to

viewing

the

allow

4

INSTR

PRESET

indicated

signal.

wavelength span

measurement

displayed

the

sidemodes

of

resets

5

the

active

the

by

on

uses

One

a

routine

noise.

automeasure

amplitude

or

a lower

example

laser

DFB

routine

marker

sensitivity

of

.

instead

scale

using

its

to

of

.

setting

this

default

in

feature

settings

is

.

Signal displayed before automeasure. Signal displayed after automeasure.

1-16

Displaying Signals (Part 1)

Automatically Tuning to Signals

To view a signal using automeasure

1. If the signal you want to tune to is not the largest input signal, perform

the following:

a. Press

4

NORMAL ON/OFF

5

, and use the front-panel knob to place the

displayed marker on the peak of the signal of interest.

b.

Press

2.

automeasure

o

T

1.

Press

2.

Press

3.

Pressing

end

span

NNNNNNNNNNNNNNNNN

Press

State

NNNNNNNN

On

is underlined.

4

UTO

A

the

N

NN

N

autmeas

N

SPAN

the

of

value

left-side

N

automeasure routine

.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

,

autmeas state

If

.

5

MEAS

N

State

N

NN

N

state

N

NN

N

AutoMan

at

N

signal

no

a

N

NN

N

.

N

NN

N

, and then

present,

is

specied

the

.

nal

softkey

sets

.Use

an

span

wavelength

the numeric

NNNNNNNNNNN

Notice that the softkey label now has

Man

the span is manually selected.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

AT MKR On Off

occurs

error

selected

span

keypad to

.

enter

so that

the

at

the

underlined to indicate the

new

1-17

Displaying Signals (Part 1)

Automatically Tuning to Signals

To automeasure to a specied log scale

1.

Press the left-side

2.

3.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

autmeas state

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Pressing

DB/DIV AutoMan

NNNNNNNNNNNNNNNNN

State

.

softkey.

sets the nal amplitude scale used at the end

of the automeasure routine. Use the numeric keypad to enter the new

value.

default value

The

has

now

automeasure

o

T

1.

2.

3.

the

Press

N

Press

autmeas

Pressing

to

tune

N

NN

N

AT MKR

the

N

underlined to

Man

left-side

N

state

NN

N

wavelength

is 10

to

N

State

N

NN

N

NN

On Off

dB-per-division. Notice

that

wavelength

.

specied

a

N

softkey

indicate

N

.

N

so

indicated

that

by

N

underlined causes

On

is

marker

the

that the

span

.

softkey

manually

is

automeasure

label

selected.

to

If no marker is displayed when

4

AUTO MEAS

5

is pressed, the optical

spectrum analyzer locates the largest input signal. If no signal is

present, an error occurs.

1-18

Automatically Tuning to Signals

To automeasure optimizing sensitivity

Displaying Signals (Part 1)

1.

Press the left-side

2.

3.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

autmeas state

Pressing

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

OPTSENS On Off

NNNNNNNNNNNNNNNNN

State

.

softkey.

so that

NNNNNNNN

On

is underlined.

1-19

Changing the Amplitude Scale and Units

Use the amplitude menu to change the amplitude scale and annotation.

Logarithmic and linear amplitude scales are available. Logarithmic scales

range from 0.01 to 20.00 decibels-per-division. The 10 dB-per-division scale is

the default setting. Regardless of the scale selected, the amplitude annotation

can be set to units of dBm or watts. The watt is the default unit for linear

scale; dBm is the default unit for log scale.

1-20

To change the amplitude scale

Displaying Signals (Part 1)

Changing the Amplitude Scale and Units

1.

Press the left-side

NNNNNNNNNNNNNNNNN

Amptd

softkey.

2. Perform one of the following:

N

Press

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

LOG dB/DIV

to select a logarithmic scale and enter the scale



using the knob, step keys, or numeric keypad.

NNNNNNNNNNNNNNNNNNNN

Press

LINEAR

the

N

units

Pressing

the

select

spectrum

Pressing

to select a linear scale.

amplitude

the

N

NN

N

NN

N

menu

N

UNITS

N

NN

N

NN

N

Amptd

N

.

N

AutoMan

left-side

N

A

annotation

analyzer's default

N

selects annotation

dBm

NNNNNNNNNNNNNN

WATT

selects annotation in watts.

units

N

NN

N

softkey

NN

.

N

allows

automatically

setting.

in

T

1.

2.



o

Press



change

the

The

.

decibels

optical

N

Auto

relative

spectrum

N

selection

to

analyzer

is

mW

1

the

.

to

optical

1-21

Understanding Multiple-Order Responses

HP 71450B/1B/2B optical spectrum analyzers use a diraction grating to

separate the input wavelengths spatially. Because diraction gratings operate

in multiple modes, the display may show multiple images of the input signal.

These multiple images depend on the input wavelength. Understanding the

relationship between input wavelength and displayed images enables you to

interpret the display correctly.

Image wavelength

input

depends

on

wavelength

The following table shows the relationship between input wavelength and

also

can

causes

1400 nm.

result

images

displayed

1500

a

,

Also

sources

Light

displayed

nm,

600

images

nm

outside

multiple

nm,

900

A

.

laser

images

1200

nm

700

displays

the

.

nm,

Input

1200 nm

laser

at

nm

600

example

or

F

1500

and

Wavelength

nm

850





displays at

nm

1500

1700

to

a

nm.

Versus

Wavelengths

Displayed

both 700

nm.

750

and

range

input

nm

300

at

laser

Multiple Images

of

Responses



2

,



,

2

nm and

nm

in

at

1-22

Displaying Signals (Part 1)

Understanding Multiple-Order Responses

The following gures show the displayed response of a 632.8 nm helium-neon

laser. In the gure on the left, both the laser response and its image are

visible. In the gure on the right, the span is reduced around the 1265.6 nm

image. Without an understanding of multiple-order responses, this multiple

image could be mistaken for a true response.

Full

span

view:

laser

and

1265

nm

image.

Image

response

at

1265

nm

1-23

Displaying Signals (Part 1)

Understanding Multiple-Order Responses

In the following gures, a 1319 nm Fabry-Perot laser results in a sub-multiple

image at 659.5 nm. However, unlike the multiple image shown in the

previous gures, the Fabry-Perot laser's sub-multiple image cannot be seen in

full span. (See the gure on the left.) If the stop wavelength is set below 900

nm as shown in the gure on the right, the sub multiple appears. This is due

to the grating order used for this sweep. The following paragraphs discuss

grating orders.

In full-span sweeps:



Multiple images are displayed



Sub-multiple images are

not

displayed

Full

span

view:

1-24

sub-multiple

not

shown.

Sub-multiple

response

nm

660

at

Displaying Signals (Part 1)

Understanding Multiple-Order Responses

The mode used depends

on instrument settings

test

to

order

the

Change

sub-multiple

images

The optical spectrum analyzer's internal monochromator operates in either

the 1stor 2ndorder diraction-grating mode. The mode selected is based on

the following instrument conditions:

Fullspan . . . . . . . . . . . . . . . . . . . . .............................1storder

Stop

<

900 nm (RES BW = 10 nm) ..........................1storder

Stop

<

900 nm (RES BW6= 10 nm) ......................... 2ndorder

The position of the diraction grating for the 2ndorder (600 nm | 899 nm)

is the same as the 1storder (1200 nm | 1798 nm). Both the sub-multiple

responses of input signals in the 1200 | 1798 nm range and 2ndorder

responses (the desired response) in the 600 | 899 nm range are displayed.

.

sweep

optical spectrum

The

Notice

greater

If

the

for

always

that in

than if

optical

the

resolution

sub-multiples

sets

sub-multiple

full span

nd

2

spectrum

bandwidth

.

st

1

the

not

and

analyzer never

st

(1

order),

is used.

order

analyzer's

not

is

N

NN

N

Press

ORDER

mode

order

response

true

a

N

.)

switches the

the monochromator

wavelength

stop

10

N

AutoMan

If

nm),

N

NN

N

the

N

nd

2

order

N

that

so

displayed

.

order during

loss near

less

is

used,

is

N

NN

N

is

Man

disappears

image

a

600 nm

nm

900

than

you

and

underlined.

,

can

it is

is

(and

test

(This

a

2ndorder: sub-multiple shown.

1storder: sub-multiple not

shown.

1-25

Displaying Signals (Part 1)

Understanding Multiple-Order Responses

To test for sub-multiples

1. Ensure that the stop wavelength is set to 900 nm or less.

2. Ensure that the resolution bandwidth is not 10 nm.

NNNNNNNNNNNNNNNNN

3. Press the left-side

4.

5.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

MORE 1 of 4

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

ORDER AutoMan

optical

The

diraction

image

the

If

6.

State

spectrum

grating

mode

disappears

softkey.

and then

so that

analyzer

to

a

is

it

,

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

MORE 2 of 4

NNNNNNNNNNN

Man

is underlined.

changes

st

1

the

order

sub-multiple

from

.

image

.

using

.

the

nd

2

order

1-26

Displaying Signals (Part 1)

Understanding Multiple-Order Responses

1-27

Aligning the Optical Spectrum Analyzer

Alignment is easy to

perform

Extended

multiple

alignments

wavelengths

The automatic alignment adjusts the mechanical position of the optical

spectrum analyzer's internal optical components. This ensures the amplitude

accuracy of your measurements.An

4

AUTO ALIGN

5

takes approximately 20

seconds to complete and should be performed whenever the optical spectrum

analyzer has been:



Moved.

within

press

will

.

not

the

a

of

can

remove

600

single

be

to

removed

the

Subjected



armed

W



alignment

The

input

nm

needed,

If

described

as

large environmental

to

the start

up at

requires

Alignment

.

range

compensation

the

section.

this

in

of each

light

a

is

temperature changes

day.

source

be

accomplished

determined

instrument

(An

displayed

with

alignment

the

by

preset

the

alignment.)

within

alignment

the

built-in

002

performed

to

,

1700

Normally

600

occurs at

at

extended

An

white-light

white-light source

alignment

the

nm

wavelength

the

alignment

source

input

or

is

range

is

an

used,

occurs

However

.

indicated

available

external

equally

17

largest

the

on

,

the

by

using

white-light

spaced

a

if

marker

either

input

marker

.

the

source

alignments

signal

displayed,

is

Option

the

If

.

are

located

002

Option

between 900 nm and 1700 nm. If an external white-light source is used,

several equally-spaced alignments are performed with the alignments

separated by no more than 50 nm.

1700

key.

the

1-28

Displaying Signals (Part 1)

Aligning the Optical Spectrum Analyzer

To align at largest input signal

1. Display a light-source response on the optical spectrum analyzer.

2. Perform one of the following steps:



Press

4

AUTO ALIGN



Press the left-side



Press the left-side

N

extnded

N

align

5

.

NNNNNNNNNNNNNNNNN

Amptd

softkey and then

NNNNNNNNNNNNNN

Misc

N

,

softkey followed by

N

and then

N

MANUAL

N

ALIGN

N

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

AUTO ALIGN

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

MORE 1 of 3

N

.

,

NNNNNNNNNNNNNNNNNNNNNNN

service

,

align

o

T

Display

1.

markers

no

If

2.

4

NORMAL ON/OFF

the

Use

3.

alignment

the

4. Press

4

AUTO ALIGN

the

at

light-source

a

are

.

5

front-panel

use

to

marker

response

displayed

knob

.

5

.

to

on

delta markers

if

(or

the

place

the

optical

marker

spectrum analyzer

are displayed),

that

signal

the

on

.

press

you

want

1-29

Displaying Signals (Part 1)

Aligning the Optical Spectrum Analyzer

To align with Option 002 internal light source

This procedure requires that your optical spectrum analyzer is equipped with

the Option 002 built-in white light source. Once started, the alignment takes

about 2 to 3 minutes to complete.

1. Use a ber-optic cable to connect the optical spectrum analyzer's

SOURCE OUTPUT

On HP 71450B/2B optical spectrum analyzers,the

INPUT

2. Press

3.

Press

4.

Press

align

o

T

procedure

This

the

to

connector will be labeled

the left-side

N

MORE

N

NN

N

LIGHT

W

with

optical

and

N

NN

N

of

1

N

ALIGN

an

requires

spectrum

MONOCHROMATOR INPUT

N

NN

N

NN

Misc

N

,

3

N

NN

softkey

N

service

N

.

N

NN

N

,

and

.

external

you

that

analyzer

light source

connect

Once

.

connectors.

OPTICAL INPUT

NN

N

then

extnded

external

an

alignment

started,

the

MONOCHROMATOR

.

N

align

.

NN

N

white-light

takes

source

2 to 3 minutes to complete. The light source must have the following

characteristics:

Start wavelength

Stop wavelength

Span

:::::: :::::: ::::::::: :::::::::::::: :::::: ::::::: ::::::: :::::: ::>

:::::::::::::::::::::::::::::::::::::::::::::::::600 nm

::::::: :::::: ::::::::: ::::::::::::: ::::::: ::::::1700 nm

LIGHT

about

10 nm

1.

a

Use

optical

ber-optic

spectrum

cable

analyzer's

MONOCHROMATOR

connect the

to

On HP 71450B/2B optical spectrum analyzers

INPUT

connector

will be labeled

NNNNNNNNNNNNNN

2. Press the left-side

NNNNNNNNNNNNNNNNNNNNNNNNN

Press

NNNNN

MORE 1 of 3

3.

Misc

NNNNN

,

softkey.

NNNNNNNNNNNNNNNNNN

NNNNN

service

, and then

1-30

external

white-light

INPUT

,the

OPTICAL INPUT

NNNNNNNNNNNNNNNNNNNNNNNNN

NNNNN

extnded align

source

connector

.

MONOCHROMATOR

.

NNNNNNNNNNN

.

to

the

Displaying Signals (Part 1)

Aligning the Optical Spectrum Analyzer

4.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

AUTOPTS ALIGN

.

To remove alignment osets

N

PRESET

N

NNNNNNNNNNNNNN

Misc

NNNNNNNNNNNNNNNNNNNNNNN

,

N

NN

.

softkey.

service

, and then

1.

Press the left-side

2.

3.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

MORE 1 of 3

N

Press

ALIGN

NN

N

NN

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

extnded align

.

1-31

Calibrating the Optical Spectrum Analyzer

Calibrating the optical spectrum analyzer ensures maximum wavelength and

amplitude accuracy for your measurements.

Verify factory

calibration once every

two years

erform user

P

calibration

to improve

accuracy

Your optical spectrum analyzer has been calibrated at the factory across its

full wavelength range.You should verify this calibration once every two years

using the automated procedures located in the optical spectrum analyzer's

Installation and Verication

manual. These factory calibration factors are

stored in non-erasable memory and are always applied to the measured data.

calibration described

The

amplitude

and

avelength

W

the

accuracy

Characteristics"

wavelength)

and

Calibration

in this

specied

as

chapter

.

single-frequency

power

menu

calibrations

from both

section

in

User

laser

the

can

eference

R

the

calibrations

within

performed

are

N

Waveln

improve

manual's

require

the

N

and

wavelength

a stable

to

600

separately

N

Amptd

\Specications

1700

menus

and

(amplitude

nm range

You

.

can

.

access

1-32

Displaying Signals (Part 1)

Calibrating the Optical Spectrum Analyzer

Locating the calibration signal

During a calibration, the optical spectrum analyzer defaults expect a signal within the following limits:

Power .........................................05 dBm65dB

Wavelength ........................................130062nm

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

If your signal is not within these limits, use

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

WAVELEN FOR CAL

to enter the wavelength. If you calibrate only power, the approximate

POWER FOR CAL

to enter the power and

wavelength of the source must also be entered. If you calibrate only wavelength, the approximate

power of the source must also be entered. Of course, if you are calibrating both wavelength and

power

approximate

the

obtain

to

markers

use

can

ou

Y

values.

exact

enter

will

you

,

wavelength

and

power values.

The Calibration menu

1-33

Displaying Signals (Part 1)

Calibrating the Optical Spectrum Analyzer

The optical spectrum analyzer's maximum calibration adjustment is about 2

nm in wavelength. If a larger adjustment is attempted, error 2023,

Cal signal

is displayed. To ensure the success of a wavelength calibration,

Illegal

the entered power-calibration value must be close to the calibration signal's

power level. This is true even though you may not perform a power

calibration.

At any time, you can prevent the use of either wavelength or power

calibration data. You can also reenter or erase the calibration from memory.

Because the optical spectrum analyzer is slightly polarization sensitive, power

calibrations should be performed by persons knowledgeable on the eects of

polarization on optical power measurements. During a power calibration,

. Then,

and

cables

meter

connected

changes

to

source's

light

the

ber-optic cable

the

optical

the

polarization,

output

spectrum

output

the

power

disconnected

is

analyzer

power

is

Because

.

may

rst

from

vary

measured

power

the

moving

.

a

with

meter

ber-optic

power

1-34

Displaying Signals (Part 1)

Calibrating the Optical Spectrum Analyzer

To calibrate wavelength

1. Measure the wavelength of a precision single-mode laser between 600 to

1700 nm using a wavelength meter. Enter the wavelength in the space

provided below.

wavelength: nm

STP

at

and

is

pressure

wavelength

the

to

is calibrated

in

acuum

v

wavelength of

Measure the

.

vacuum environment.

a

at the

if

factory to

wish

you

the

to

read

source

have

wavelength

to

air

in

optical

the

air

in

consistent

be

spectrum

standard

at

analyzer

with

factory

read

calibration

Factory

optical

The

temperature

calibration.

wavelength

spectrum analyzer

Enter

corrected

Connect

2.

the

laser

to

the

optical

spectrum

analyzer's

connector.

3.

4.

5.

6.

7.

8.

9.

AUTO

4

Press

AUTO

Press the left-side

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

MORE 1 of 2

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

WAVELEN FOR CAL

numeric

the

Use

1.

step

NNNNNNNNNNNNNNNNNNNNNNNNN

N

Press

POWER FOR CAL

4

Press

MEAS

ALIGN

perform

to

5

align

to

5

N

Waveln

NNNNNNNNNNNNNNNNNNNNNNNNNN

,

keypad

NNNNNNNNNNNNNNN

an

the

NN

N

softkey.

cal menu

.

enter

to

.

automatic

optical spectrum

, and then

the

measurement

analyzer.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNN

cal setup

wavelength value

10. A marker should be positioned on the peak of the

the marker amplitude value shown at the top of the display

numeric keypad to enter this value

.

front-panel

signal.

of the

.

recorded

laser's response

and use the

,

input

in

.Read

1-35

Displaying Signals (Part 1)

Calibrating the Optical Spectrum Analyzer

11.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

prev menu

routine.

The calibration routine takes several seconds to complete.

and then

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

CAL WAVELEN

to start the calibration

1-36

Displaying Signals (Part 1)

Calibrating the Optical Spectrum Analyzer

To calibrate power and wavelength

This procedure calibrates both power and wavelength. You can also use it

to calibrate only the power. In this case, simply enter the wavelength of

the source as measured with the optical spectrum analyzer in step 1 of this

procedure.

The optical spectrum analyzer stores separate user power-calibration osets

for the power-meter instrument mode and other instrument modes.User

power-calibrations that are performed in the optical spectrum analyzer mode

apply

o

T

.

mode

calibrate

,

you

If

.

following

the

calibrate

steps may

NN

readings

NN

the power-meter

)in

do not

user-calibration corrections

power (

the

not

aect amplitude

N

NN

CAL POWER

power-meter

power

apply

in

.

NN

N

power-meter

in

in power-meter

instrument

mode

instrument

instrument mode

the

of

some

,

Ensuring

During this

changes the

amplitude

procedure

polarization of

accuracy

avoid

,

the

moving

light

the

which

ber-optic

aects

cables

power

whenever

possible

measurements.

Moving

.

ber-optic

cables

1. Measure the wavelength of a precision single-mode laser between 600

and 1700 nm:



Use a wavelength meter if you're calibrating both power and

wavelength.

Use



not

optical

the

wavelength.

spectrum

analyzer

you're

if

calibrating

the power

and

wavelength: nm

1-37

Displaying Signals (Part 1)

Calibrating the Optical Spectrum Analyzer

Factory calibration is at STP

The optical spectrum analyzer is calibrated at the factory to read wavelength in air at standard

temperature and pressure. Measure the wavelength of the source in

calibration. Enter the wavelength in

vacuum

if you wish to have the optical spectrum analyzer read

air

to be consistent with factory

wavelength corrected to a vacuum environment.

output

2. Connect

the laser

polarization controller

polarization

to a

controller

power meter

Connect

.

the

of

the

djust the

A

3.

power meter

the

on

the

djust

A

4.

power

the

there

If

values

recorded

appropriate

Calculate

5.

the

using

4

averag e power

achieve

the

to

power

polarization controller

. Record

maximum

achieve

polarization

Record

.

meter

controller

the

to

power

level

minimum

between

the

that

wavelength.

power

two

Record

2

above

source

of

equation.

change

check

,

the

signicant

a

is

the

for

average

the

following

minimum power+maximum power

=

the

on

level

power:

minimum

a

the

on

power:

maximum

the

polarization

readings

result

the

maximum

following

the

following

state

recorded

below:

power

line:

and

controller

in

reading

line:

reading

minimum

3

steps

dBm

is

and

average power: dBm

6. Disconnect the ber-optic cable from the power meter, and connect the

cable

Press

7.

8. Press

9. Press

optical

the

to

4

MEAS

UTO

A

4

AUTO ALIGN

4

RES BW

5

spectrum

display

to

5

to align the optical spectrum analyzer

analyzer's

laser's

the

input connector

response

, and enter a 0.5 nm bandwidth.

.

on

10. Press

11. Press

1-38

4

PEAK SEARCH

4

5

, and enter a wavelength span of 1 nm.

SPAN

5

and then

4

TO CENTER

5

.

Displaying Signals (Part 1)

Calibrating the Optical Spectrum Analyzer

12. Press

13. Press

14.

15.

4

PEAK SEARCH

4

5

, and enter a wavelength span of 0 nm.

SPAN

Press the left-side

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

LOG dB/DIV,415

scale.

16. Press the left-side

17.

18.

19.

20.

21.

22. Record

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

SWPTIME AutoMan,415,405

polarization

the

djust

A

This

djust

spectrum

sets

4

PEAK

4

.

5

1

polarization

the

spectrum

marker-delta

the

polarization

the

SEARCH

optical

Press

A

optical

5

and then

NNNNNNNNNNNNNNNNN

Amptd

,and

NNNNNNNNNNNNNNNNNNNN

BW,Swp

controller

analyzer

and

,

5

controller

analyzer

softkey.

NNNNNNNN

softkey.

.

for

record

a

to

power

4

TO CENTER

dB

to select a 1 dB logarithmic amplitude

5

.

NNNNN

, and then

\peak"

to

a maximum

power level

the

maximum

\dip"

to

minimum

on

level

s

.

trace

the

power reading.

indicated by

power:

trace

the

power

the

value

following

displayed

.

line:

1 power: dBm

on

the

on

the

marker:

dBm

the

average

23. Use

the values

displayed power

recorded

as shown

in

steps

the

in

and

19

following

to

22

equation.

calculate

the

Record

below:

1

averag e power=maximum power

power

0

2

average power:

24.

25.

26. A

the left-side

Press

N

NN

N

Press

MORE 1 of 4

NNNNNNN

N

On

is underlined.

djust the polarization controller to achieve a displayed Amplitude Meter

N

Amptd

NN

N

NN

N

softkey.

N

,

N

NN

N

MORE 2 of 4

N

NN

N

NN

N

, and then

N

NN

N

AMETER On Off

N

NN

N

NN

N

power level equal to the power level recorded in step 23.

NN

N

the

N

result

N

so that

1-39

Displaying Signals (Part 1)

Calibrating the Optical Spectrum Analyzer

Ensuring amplitude accuracy

It is very important not to move the ber-optic cables during the remaining steps of this procedure.

27. Press the left-side

NNNNNNNNNNNNNNNNNNNNNNNNNN

28.

29.

30.

cal menu

Use

Press

Select



you're

If

N

CAL



you're

If

NN

N

CAL

numeric

the

NN

N

WAVELEN

one

N

NN

N

WAVELEN

N

POWER

,

NN

or

calibrating

N

calibrating the

N

Waveln

NNNNNNNNNNNNNNNNNNNNNNNNNNNNN

cal setup

keypad

N

both

N

FOR

N

NN

of

CAL

the

NN

N

.

N

.

softkey. Then, press

,andthen

enter

to

N

Enter

.

following

wavelength,

,

power

To turn o user-calibration

NNNNNNNNNNNNNNNNN

NNNNNNNNNNNNNNNNNNNN

1. Press the left-side

N

2.

3.

4.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

MORE 1 of 2

N

NN

N

Press

power calibration.

the

PWR

CAL

NNNNNNNNNNNNNNNNNNN

Press

WL CAL On

NN

N

NN

N

On

NNNNNNNNNNNNNNNNNNNNNN

Amptd

and then

N

Off

softkey.

NN

N

so

so that

N

NNNNNNNNNNNNNNNNNNNNNNNNN

cal menu

N

that

Off

NNNNNNNNNNN

Off

N

the wavelength calibration.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

POWER FOR CAL

the

power

steps

level

wavelength

to complete

N

press

N

press

N

NN

N

underlined

is

is underlined

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

MORE 1 of 2

.

recorded

in

the calibration:

NN

N

menu

N

NN

N

to

and

menu

and then

prevent

N

NN

N

to prevent the use of

,

step

then

the

5.

1.

use

of

The

USERCAL

annotation is removed from the screen indicating that the

user-calibrations are disabled. The factory-installed calibrations are still used.

1-40

To erase user-calibration

Displaying Signals (Part 1)

Calibrating the Optical Spectrum Analyzer

1. Press the left-side

2.

3.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

MORE 1 of 2

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

USERCAL PRESET

NNNNNNNNNNNNNNNNN

Amptd

NNNNNNNNNNNNNNNNNNNNNNNNNN

,

cal menu

softkey.

.

, and then

NNNNNNNNNNNNNNNNNNNNNNNNNNNNN

cal setup

.

1-41

Cleaning Connections for Accurate

Measurements

Accurate and repeatable measurements require clean connections. Use the

following guidelines to achieve the best possible performance when making

measurements on a ber-optic system:



Keep connectors covered when not in use.



Use dry connections whenever possible.



Use the cleaning methods described in this section.

CAUTION

care in



Use

When

sure

adapter

or

damaged

,

inserting a

the

that

.

the

of

connections

good



Because

ensure

gaps

index-matching

connections

dry

Use

connections

Dry

Diamond

40

,

return

dB

(and can

ackard

example

has

improve

Hewlett-P

handling all

ber-optic

ber-optic connector

does

end

ber

cores

of

size

small

oor

P

.

contamination,

,

ends

ber

Dry

be

used

.

connectors

with

compounds

.

can

HMS-10/HP

better

or

loss

degrade) performance

strongly

recommends that

connectors

touch

not

used

connections

are

physically

FC/PC,

,

making

,

into a

the

in

easier

DIN,

a

.

front-panel

outside

optical

result

and

of the

bers

from

improper

clean

to

contacting

ST).

and

connection

wet

index matching

adapter

mating connector

care must

,

misalignment,

core

and

use

to

and

connectors

connection

dry

a

If

probably

will

compounds NOT

make

,

be

removal

keep

(for

used

of

clean.

not

be applied to their instruments and accessories. Some compounds,suchas

gels, may be dicult to remove and can contain damaging particulates.If

you think the use of such compounds is necessary, refer to the compound

manufacturer for information on application and cleaning procedures.

Cleaning

Accessories

Item HP Part Number

Isopropyl alcohol 8500-5344

Cotton swabs 8520-0023

Small foam swabs 9300-1223

Compressed dust remover (non-residue) 8500-5262

to

air

1-42

Inspecting

Cables

Fiber-Optic

Consistent

indication

insertion

the

your

test

you

the

and

future

receipt,

in

Connector

lightwave

as

little

as

another

is

better

the

physically

although

Dust Caps Provided with Lightwave Instruments

measurements

have

you

that

and/or

loss

cables

the

retain

degradation

any

if

insertion)

(or

dB

.

of

connector

0.1

important

larger

(the

contacting

dB

40

to

30

Cleaning Connections for Accurate Measurements

Item HP Part Number

Laser shutter cap 08145-64521

FC/PC dust cap 08154-44102

Biconic dust cap 08154-44105

DIN dust cap 5040-9364

HMS10/HP dust cap 5040-9361

ST dust cap 5040-9366

lightwave

your

with

connections

good

of

is

values

It

.

return

common.

loss

for

data

occurred.

has

important

one

are

performance

a measure

is

, the

loss

have

return

accessories

and

measured

loss

Typical

with high

loss

factor

the

connectors

more

is

However

.

lightwave

your

insertion

comparison,

for

than

less

of

smaller the

return

equipment

you

,

cables

and

loss

you

performance

dB

1

connectors

reection:

reection).

better

losses

Displaying Signals (Part 1)

good

a

are

to know

wish

may

accessories

or

upon

be

loss

able

return

will

characteristic

sometimes

and

,

loss

of

Return

.

less

the

than 50

loss

reection

best

The

dB,

to

tell

of

.If

a

You can visually inspect your cables

Although it is not necessary, visual inspection of ber ends can be helpful. Contamination or

imperfections on the cable end face can be detected as well as cracks or chips in the ber itself. Use

a microscope (100X to 200X magnication) to inspect the entire end face for contamination, raised

metal,

Visible

keep

dents

or

imperfections

bers

the

in the

from

metal

touching

not

contacting).

imperfections.

other

y

an

as

well

as

not

y

ma

core

ber

the

Inspect

performance (unless

aect

ber for

the

cracks

imperfections

the

chips.

and

1-43

Displaying Signals (Part 1)

Cleaning Connections for Accurate Measurements

To clean a non-lensed connector

CAUTION

Do not use any type of foam swab to clean optical ber ends.Foam swabs

can leave lmy deposits on ber ends that can degrade performance.

1. Apply isopropyl alcohol to a clean lint-free cotton swab or lens paper.

Cotton swabs can be used as long as no cotton bers remain on the ber

end after cleaning.

2. Before cleaning the ber end, clean the ferrules and other parts of the

connector

Apply

3.

Clean

4.

paper

Some

remove

them.

.

isopropyl

ber

the

and

back

amount

particles

This

alcohol

with

end

across

forth

wiping

of

when

technique

new

a

to

swab

the

mild

or

application

remove

can

clean lint-free

lens paper

or

several

end

ber

scrubbing

alcohol

of

displace

or

cotton swab

.Move

times.

ber

the

of

alone

particles

the

will

swab

end

not

smaller

or lens

or

help

can

remove

than

paper.

lens

micron.

Immediately

5.

lens

6. Blow

ltered, dry

ber

the

.

paper

across the

, compressed

end face

ber

the

dry

connector end

.

end

air.

a

with

face from

Aim the

clean,

dry

distance

a

compressed

lint-free

,

gas

of

6

at

cotton

to

a

swab

inches

8

shallow

using

angle

Nitrogen gas or compressed dust remover can also be used.

one

or

to

CAUTION

Do not shake,tip, or invert compressed air canisters, because this releases

particles in the can into the air. Refer to instructions provided on the

compressed

soon

As

7.

air

as

canister

the

.

connector

cover it

connect

,

dry

is

or

for

.

use

later

1-44

Displaying Signals (Part 1)

Cleaning Connections for Accurate Measurements

To clean an adapter

1. Apply isopropyl alcohol to a clean foam swab.

Cotton swabs can be used as long as no cotton bers remain after

cleaning. The foam swabs listed in this section's introduction are small

enough to t into adapters.

Although foam swabs can leave lmy deposits, these deposits are very

thin, and the risk of other contamination buildup on the inside of

adapters greatly outweighs the risk of contamination by foam swabs.

.

swab

adapter

foam

with

clean,

a

dry

,

foam

swab

.

2. Clean

3. Dry

the adapter

the inside

with the

of the

be

air.

used.

this

on

releases

the

, compressed

ltered,

compressed

the

.

using

.

air

dust

Refer

adapter

,

the

air

the

or

gas

or

,

tip

can

canister

compressed

invert

into

through

Blow

4.

Nitrogen

N

O

I

T

U

A

C

Do

particles

in

shake

not

compressed

dry

also

remover

air

to

can

because

canisters

,

instructions provided

To test insertion loss

Use an appropriate lightwave source and a compatible lightwave receiver to

test insertion loss. Examples of test equipment congurations include the

following equipment:

Option

71451A

71450A

HP



built-in



HP 8702 or HP 8703 lightwave component analyzer system



HP 83420 lightwave test set with an HP 8510 network analyzer



HP 8153 lightwave multimeter with a source and power sensor module

or HP

white

light

source.

optical

spectrum

analyzers

with

002

1-45

Displaying Signals (Part 1)

To test return loss

Use an appropriate lightwave source, alightwave receiver, and lightwave

coupler to test return loss. Examples of test equipment congurations include

the following equipment:



HP 8703 lightwave component analyzer



HP 8702 analyzer with the appropriate source, receiver, and lightwave

coupler

8504 precision



HP

8153 lightwave



HP

conjunction with

81554SM

HP



reectometer

multimeter with

a lightwave

source

dual

and

coupler

81534A

HP

source

a

power

and

return loss

sensor

module

in

1-46

2

Displaying

Signals

(P

art

2)

Displaying Signals (Part 2)

In this chapter, you'll learn how to control instrument settings manually.

Normally, sweep time and bandwidths are automatically controlled to ensure

a calibrated display. However, manual control allows closer inspection of

input signals.

If an

UNCAL

message is displayed after manually changing a setting, the

display has become uncalibrated. Trace data may not meet specications.For

example, amplitude readouts may not be accurate. Change the setting so

automatic

and

All

5

.

to

settings

save

can

UNCAL

that

coupling by

be returned

addition,

In

instrument

disappears

pressing

to their

chapter

this

.

setups

Each

.

softkey

its

coupled

shows

individual

that

so

by

mode

how

setting

N

Auto

pressing

to pulse

can

N

underlined.

is

4

INSTR

light sources

returned

be

PRESET

2-2

Displaying Signals (Part 2)

Contents

Resolving Wavelengths ....................................2-4

To resolve closely spaced signals . . . . . . . . . ................ 2-6

To change the RB/span ratio ............................ 2-6

Reducing Displayed Noise .................................2-8

To reduce the displayed noise . ......................... 2-11

Increasing Dynamic Range ................................ 2-12

To increase dynamic range . ............................ 2-13

To disable chop mode ................................. 2-14

Controlling Sweeps ...................................... 2-16

To set continuous or single sweeps ...................... 2-19

To set the sweep time ................................. 2-20

2-20

.

sweep

the

stop

o

T

reduce

o

T

Triggering Sweeps

use freerun

o

T

use video

o

T

use line

o

T

use

o

T

delay

o

T

Saving

save

o

T

protect

o

T

select

o

T

sweep

triggering .

external

the

Instrument

recall

or

measurement

the

.

retrace

..

triggering .

.

sweep

power-on

.

Setups

measurement

a

time

.

state

2-21

.

..

.

2-22

.

..

.

2-25

.

..

.

2-25

.

..

.

2-26

.

..

.

2-26

.

..

.

2-26

.

..

.

..

.

2-27

.

..

.

2-27

.

..

.

state

2-28

.

..

.

les

2-28

.

..

.

2-3

Resolving Wavelengths

Resolution bandwidth

determines wavelength

resolution

The ability to display two closely spaced signals, in wavelength, as two

distinct responses is determined by resolution bandwidth. The resolution

bandwidth can be set to one of the following values: 0.08, 0.1, 0.2, 0.5, 1,

2, 5, or 10 nanometers. (The 0.08 nm lter does not guarantee warranted

accuracies and can only be entered using the numeric keypad.)

Normally, the resolution bandwidth is coupled to the span in a preset 0.01:1

a

by

set

1%

between

asterisk

an

are

and

40%

This

.

ratio

bandwidth

available

span.)

the

of

Manually



Changing



Manually

resolution

means that

that

value

discrete

in

ou

Y

setting

resolution

the

entering

bandwidths

the

to

the optical

is 1%

steps

alter

can

the

resolution

a

and

screen

of the

actual

the

,

this

resolution

bandwidth

span.

annotation.

spectrum analyzer

span setting.

bandwidth

one

behavior

by

bandwidth.

span

to

disengages

condition

This

attempts to

(Because bandwidths

between

be

will

methods:

two

of

.

ratio

coupling

the

indicated

is

Wide Resolution Bandwidth Narrower Resolution Bandwidth

2-4

Displaying Signals (Part 2)

Resolving Wavelengths

The resolution bandwidth lter determines the shape of the displayed

response. If the bandwidth is large, the top of the signal is at and the signal

wavelength is not easily identied. The following gure shows three modes

of a Fabry-Perot laser. Each mode is displayed using a dierent resolution

bandwidth. As the bandwidth is decreased, the signal's wavelength becomes

evident.

2-5

Displaying Signals (Part 2)

Resolving Wavelengths

To resolve closely spaced signals

1.

Press the left-side

2.

3. Press

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

RES BW AutoMan

495

to reduce the resolution bandwidth. Or, use the knob or numeric

NNNNNNNNNNNNNNNNNNNN

BW,Swp

.

softkey.

keypad to enter a reduced resolution bandwidth.

Valid bandwidths are 0.08, 0.1, 0.2, 0.5, 1, 2, 5, and 10 nanometers.

numeric

the

and

step

using

,

then

keys

press

NN

N

RB/SPAN

or

,

N

the

N

NN

numeric

N

RES

N

The

return

o

T

softkey so

change

o

T

1.

Press the

2.

Press

Enter

3.

bandwidth

0.08

autocoupled

to

that

N

Auto

N

the

left-side

N

NN

N

MORE

RB/span ratio

a

of

1

can

resolution

N

underlined.

is

RB/span

N

BW,Swp

N

NN

N

,

3

MORE

using the

N

NN

N

NN

only

ratio

softkey

N

of

2

entered

be

bandwidths

.

N

NN

N

,

3

knob,

keypad.

NN

N

BW

N

NN

N

RATIO

keypad.

N

NN

AutoMan

N

.

NN

N

The default ratio is:

2-6

0.01

.

Displaying Signals (Part 2)

Resolving Wavelengths

2-7

Reducing Displayed Noise

Sensitivity reduces

displayed noise

Higher sensitivity settings reduce the displayed noise oor. Although this

method often reveals signal that might otherwise be hidden, it also results in

longer sweep times.For more information on changing the sensitivity, refer

to Chapter 1.

Low

sensitivity

hides

sidemodes.

Higher

sensitivity

reveals

sidemodes.

2-8

Displaying Signals (Part 2)

Reducing Displayed Noise

Video bandwidth

reduces displayed noise

The video bandwidth determines the level of the displayed noise. Decreasing

the video bandwidth reduces the displayed noise. Normally, the video

bandwidth is coupled to the sensitivity. Manually entering a video bandwidth

breaks this coupling. Manual video bandwidths are indicated by an asterisk

(*VB) next to the screen annotation.

The video bandwidth can be manually set from 100 mHz to 3 kHz up to a

maximum value of 400 kHz. In the autocoupled mode, the video bandwidth

has an extremely wide range. This allows the optical spectrum analyzer to

avoid unnecessary ltering that would reduce the sweep speed more than

required. The narrowest video bandwidths are obtained using one of the

following methods:

N

NN

N

NN

N



Entering



Reducing



Turning

following

The

modes

a

the

autoranging

hidden

video

lower

reference

gures

the

by

bandwidth

sensitivity

level.

o (using

how

show

.

noise

manually

.

value

N

NN

the

AUTORNG

video

N

ltering

with

N

to

.

reveal

side

AutoMan

BW

VID

N

NN

N

On

can

Off

be

softkey

used

3 kHz video ltering. 10 Hz ltering.

2-9

Displaying Signals (Part 2)

Reducing Displayed Noise

Video averaging

reduces displayed noise

Video averaging allows you to view signals that are within 6 dB of the

displayed noise oor. This eliminates the need to increase sensitivity at the

expense of longer sweep times. Video averaging reduces displayed noise by

averaging the response of multiple trace sweeps. The resulting display shows

the value of the averaged traces.

Video averaging operates on trace A; it does not aect traces B or C. The

optical spectrum analyzer keeps a running average using trace data from

the number of sweeps you specify. The default average uses 100 sweeps.

However, you can change the average from 1 to 10,000 traces. Use the

front-panel keys to change the number of trace sweeps averaged.

averaging

can

then

on

you

again.

Once

o

started,

and

averaging automatically

restart

Also

averaging

any

,

restarts the

any

the

change

in

video averaging.

by

time

instrument's

turning

video

state

that

aects

2-10

Page

Menu

races

T

of

3

To reduce the displayed noise



Via sensitivity:

that

N

NN

N

AutoMan

video

NNNNNNNNNNNNNNNNN

Amptd

NNNNNNNNNNNNNN

Auto

N

BW,Swp

N

softkey.

and use the knob, numeric keypad, or

underlined.

is

N

NN

N

bandwidth.

softkey

N

and

use

.

the

1.

Press the left-side

2.

Via



1.

2.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

SENS AutoMan

reduce the sensitivity.

To return to autocoupled sensitivity, press the

softkey

bandwidth:

video

the

Press

N

Press

VID

reduce

to

so

left-side

N

BW

the

knob

numeric

,

Displaying Signals (Part 2)

Reducing Displayed Noise

495

key to

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

VID BW AutoMan

4

keypad,

or

5

9

key

bandwidths

softkey

N

then

and

N

NN

N

to

video

that

so

softkey

mode

NN

N

Off

to

.

N

MORE

softkey so that

N

and

N

Auto

enter

N

2of

then

autocoupled

return

o

T

N

VID

video

Via



1.

Press

be

must

Press

2.

3.

Press the

4. Enter the number of sweeps to average the displayed trace.Or,usethe

default of 100 trace averages.

5.

Press

time

any

to

N

NN

N

AutoMan

BW

averaging:

clear-write

N

NN

N

1of

N

NN

N

On

N

left-side

the

in

N

MORE

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

VID AVG On Off

NN

N

NN

N

AVG

VID

.

N

NN

N

Traces

N

4

N

Off

,

N

NN

N

NN

N

underlined.

is

Traces

the

N

4

.

NNNNNNNN

On

is underlined.

N

NN

restart

to

On

menu.

averaging

Trace A

the

press

at

2-11

Increasing Dynamic Range

Dynamic range determines the ability to view small signals in the presence of

a large signal. Large input signals can reduce dynamic range by producing

stray light inside the optical spectrum analyzer's internal monochromator.

This stray light raises the displayed noise oor, which reduces the dynamic

range.To compensate for the eect of stray light, the optical spectrum

analyzer uses a special \chop" mode. In chop mode, the optical spectrum

analyzer's photodetector is \zeroed" before each measurement. (This

eectively measures and subtracts the stray light and noise from each

measured trace

point.)

Chop mode

Although

dynamic range

its

meet

Video

.

range

mode

Chop

seconds

40

be

not

will

also compensates

mode is

chop

averaging

automatically

is

F

.

longer

or

problem.

a

for electronic

not required

specications,

further

enhances

turned

measurements

many

or

needed,

If

you

the

for

it

whenever

on

can

drift during

optical

be

can

eectiveness

the

,

disable

used

the

stray

chop

long

spectrum

enhance

to

of

sweep

and electronic

light

mode

sweeps

analyzer

the

chop

is

time

.

to

dynamic

mode.

drift

2-12

Displaying Signals (Part 2)

Increasing Dynamic Range

Chop mode is related to trace length

The sweep time at which chop mode turns on depends on the length of the displayed trace.For the

default trace length of 800 points, chop mode turns on for sweep times of 40 seconds or longer.If

the trace length is changed (as described in Chapter 8), the sweep time at which chop mode turns on

changes as indicated by the following equation:

1

sweep time

'050

ms10trace leng th

o increase

T

1.

2.

Press

seconds

40

Any

the

N

SWPTIME

sweep

This is

dynamic

left-side

N

NN

N

AutoMan

.

time of

true unless

N

NN

BW,Swp

NN

N

range

N

softkey

N

NN

and

,

40 seconds

the

N

CHOP On

N

.

use

or more

NN

N

the

N

Off

N

numeric

turns on

N

softkey

keypad

chop

set

is

to

enter

to

mode

o

as

in \To disable chop mode".

3.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

N

Press

VID AVG On Off

so that

NNNNNNN

N

On

is underlined.

Since chop mode enhances the dynamic range by subtracting very small

values of

to more

light

stray

meaningful

noise

and

display

,

.

averaging

several

sweeps

generally

operation.

described

leads

2-13

Displaying Signals (Part 2)

Increasing Dynamic Range

To disable chop mode

N

1.

Press the left-side

2.

3.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

MORE 1 of 4

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

CHOP On Off

NNNNNNNNNNNNNNNN

Amptd

.

so that

softkey.

NNNNNNNNNNN

Off

is underlined.

2-14

Displaying Signals (Part 2)

Increasing Dynamic Range

2-15

Controlling Sweeps

The optical spectrum analyzer provides a wide range of sweep times. The

sweep times range from 50 ms to a maximum value that depends on the

number of trace points used to draw the trace. This relationship is shown in

the following equation:

50

mssweep time

(1

s)(trace points

)

The default number of trace points is 800, so the maximum sweep time

is normally 800 seconds. If you change the number of trace points, the

Length

to

the

analyzer

the

Trace

length.

trace

following

maximum

sweep

Interpolation"

Sweeps

can

automatically

instrument

avelength

W



Resolution



Video



Sensitivity



ower

P



settings:

bandwidth.

level

time

Chapter

in

continuous

be

selects

span.

bandwidth.

.

top

at

becomes

8

sweep

screen

longer

information

for

single

or

times

.

The

.

based

Refer

optical

on

\Changing

to

changing

on

spectrum

coupling

and

2-16

Displaying Signals (Part 2)

Controlling Sweeps

2-17

Displaying Signals (Part 2)

Controlling Sweeps

Manual sweep times

disable coupling

Manually setting the sweep time turns coupling o. If the sweep time is

set too fast, an

UNCAL

message appears indicating the display is no longer

calibrated and that trace data may not meet specications. Increase the

sweep time until

UNCAL

disappears. If the sweep time is set too slow,

measurement times may be excessively long. Sweep times of 40 seconds

or longer use a special \chop" mode. Chop mode provides the following

advantages:



Increases dynamic range.



Stabilizes measurements against drift.



Reduces eects of stray light.

chop

about

learn

Refer

mode.

sweep

\Increasing

to

Manual sweep

screen annotation.

time

Dynamic

times are

Range"

in

indicated by

this

chapter

an

to

asterisk

(*ST)

the

2-18

Displaying Signals (Part 2)

Controlling Sweeps

Sweep retrace time can

be reduced

The sweep can be

disabled

The optical spectrum analyzer compensates for temperature-related current

drift between each sweep. Although this \zeroing" increases amplitude

accuracy, it increases the time between sweeps. If amplitude accuracy is not

critical for your measurement, you can turn o \zeroing" between sweeps

using the

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

AUTZERO On Off

softkey.

The optical spectrum analyzer performs a more complete \zeroing" when

the instrument is rst turned on. You can run this more complete routine

anytime by pressing the

NNNNNNNNNNNNNN

ZERO

softkey.

You can prevent the optical spectrum analyzer from sweeping. Although the

internal

you may

times

set

To

1.

Press

2.

NN

N



CONT

N

NN



SINGLE SWEEP

monochromator

want to

continuous

N

NN

N

the

BW,Swp

following

the

of

one

NN

N

NN

N

SWEEP

N

to

N

NN

N

rugged

is

stop the

or

softkey

use

.

continuous

to sweep

enough

sweep

single

to

.

sweeps

softkeys:

sweeping.

the measurement

withstand

range

continuous

.

once

sweeps

,

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

To repeat another single sweep, press

SINGLE SWEEP

again.

at

2-19

Displaying Signals (Part 2)

Controlling Sweeps

To set the sweep time

1.

Press the

NNNNNNNNNNNNNNNNNNNN

BW,Swp

softkey.

2. Use the knob, step keys, or numeric keypad to enter the desired sweep

time.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

To reestablish sweep time coupling, press

NNNNNNNNNNNNNN

Auto

is underlined.

disrupts

UNCAL

N

NN

N

BW,Swp

N

and

3

N

NN

so

time

sweep time

N

softkey

then

that

appears

N

MORE 2

NN

Off

Manually

calibrated

uncalibrated

the

stop

o

T

1.

Press

2.

Press

3.

Press

setting

display

the

left-side

the

N

MORE 1

N

NN

SWEEP

the

Whenever a

.

warning

sweep

N

NN

N

of

NN

N

Off

On

sweep

N

NN

.

N

NN

N

underlined.

is

SWPTIME AutoMan

coupling

the

is selected

NN

of

N

3

display.

N

.

on the

NN

N

maintain

to

used

that degrades

so that

accuracy

a

,

2-20

Displaying Signals (Part 2)

Controlling Sweeps

To reduce sweep retrace time

Reducing the sweep retrace time also decreases amplitude accuracy.

1.

Press the left-side

2.

3.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

MORE 1 of 4

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

AUTZERO On Off

NNNNNNNNNNNNNNNNN

Amptd

and then

softkey.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

MORE 2 of 4

so that

NNNNNNNNNNN

Off

is underlined.

.

2-21

Triggering Sweeps

You can select the type of trigger event used to start and synchronize each

sweep. Choices are the following:



Freerun.



Video level (zero span only).



Power line frequency.



External trigger source.

Video

the

triggering

input

signal

uses

for

is

the

direction.

signal's

a

triggering.

stable

a

nm,

0

not

occurs

detected

rising

is

freerun

When rst

turned on,

Freerun triggering

the current

display

Video

freerun

the

signal

Hysteresis

falling



of

triggering

edge

video

dBm.

and ltered

the following

direction allow

and

.

signal

minimum

trigger

the

detected

satises

Level:

100

0

Hysteresis:

crossing

Direction: whether the hysteresis is increasing (rising edge) or decreasing

the optical

ensures continuous

tuning range

occurs

only

even

applies

input

amplitude

increase

level.

spectrum analyzer

, evenly

.

span

zero

to

is

video

if

signal.

A

conditions:

specify

to

you

triggers

that

decrease

or

Preset

value

sweeps

selected.

sweep

level,

triggering

the

in

3

is

uses

timed sweeps

the

If

.

Video

occurs

hysteresis

when

,

on

.

sweep

amplitude before

signal

.

dB

span

triggering

and

Preset value

(falling edge). Preset direction is rising edge.

For example, if video hysteresis is +5 dB, and the trigger level is090 dBm,

the analyzer sweeps when the detected signal level changes from less than

dBm to

95

0

triggering

greater

the signal's

on

the falling edge

NNNNNNNNNNNNNNNNNNNNNN

Use the

trigger

VID LIN On Off

level and hysteresis oset.

.

NNNNNNNNNNNNNNNNNNNNNN

than

ositive

P

dBm.

90

0

Negative

.

edge

rising

softkey to display

hysteresis

values

indicate

lines that show the current

indicate

triggering

on

or

2-22

Displaying Signals (Part 2)

Triggering Sweeps

Maximum and minimum values

Valid trigger levels range between6300 dBm. Valid hysteresis levels range between6300 dB.

Video

trigger

and

hysteresis

lines.

2-23

Displaying Signals (Part 2)

Triggering Sweeps

External triggering uses

an external signal

External triggering synchronizes the sweep with a signal connected to the HP

70950A or HP 70951A module's rear-panel

triggering requires a TTL-compatible signal with a minimum of 0V and a

maximum of +5V.

At times, there may be a delay between the event that you want to measure

and the external trigger signal. If this delay is much larger than the sweep

time, only a portion of the desired data may be seen. To remedy this

situation, use the

to 52 ms after the trigger condition is met. Delay can be entered with 1sof

resolution. The screen shows a \" symbol whenever delay is added to the

trigger.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

TRIGGER DELAY

softkey to delay the start of the sweep up

EXT TRIG IN

connector. External

2-24

Rear

panel

of

optical

spectrum

analyzer

module.

To use freerun triggering

Displaying Signals (Part 2)

Triggering Sweeps

1.

Press the left-side

2.

To

1. Press

2.

3.

4.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

MORE 1 of 3

use video

4

AN

SP

left-side

the

Press

N

NN

N

Press

MORE

N

HYS

ositive

to

N

indicate

required

Press

P

values

hysteresis

sweeps

greater

to

Press

NNNNNNNNNNNNNNNNN

VIDEO

5.

NNNNNNNNNNNNNNNNNNNN

BW,Swp

softkey.

and then

triggering

wavelength

N

BW,Swp

N

NN

N

3

of

the

N

,

indicate

triggering

dB

+5

the

90

0

the

N

NN

N

then

and

sweep

enter

and

triggering

and

,

detected

dBm.

N

softkey

.

on

the

and set

5

,

N

1

trigger

N

NN

N

LEVEL

values

is

when

than

N

to start video triggering.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

TRIGGER FREE

span

.

NN

N

NN

N

VIDEO

the

trigger

signal

LEVEL

hysteresis

the

on

falling

edge

level

changes

level

nm.

0

to

N

and

,

required

signal's

.

0

is

softkey.

enter

rising

example

or

F

90 dBm,

from

the level

trigger

to

edge

,if

the analyzer

than

less

the

Negative

.

video

95 dBm

0

sweep

.

6. If you want to view lines that show the video trigger and hysteresis levels,

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

press

MORE 2 of 3

and then

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

VID LIN On Off

.

2-25

Displaying Signals (Part 2)

Triggering Sweeps

To use line triggering

1.

Press the left-side

2.

To

1. Connect

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

MORE 1 of 3

use external

the external

module's rear-panel

trigger

The

2.

3.

values

Press

the

N

MORE

must

left-side

N

NN

N

signal

N

1

NNNNNNNNNNNNNNNNNNNN

BW,Swp

and then

triggering

EXT TRIG

must

and

0V

be

N

NN

N

BW,Swp

N

of

and

3

trigger

be

+5V).

N

then

softkey.

NNNNNNNNNNNNNN

LINE

.

to

signal

connector

IN

TTL-compatible

N

EXT

.

NN

N

.

softkey

the

70950A

HP

.

(minimum

or

HP

and

70951A

maximum

To delay the sweep

N

of

N

NN

N

DELAY

NNNNNNNNNNNNNNNNNNN

BW,Swp

and

3

N

NN

N

,

softkey.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

then

enter the

and

MORE 2

3

of

amount

.

of

1.

Press the left-side

2.

3.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

MORE 1

N

NN

Press

TRIGGER

N

NN

N

Up to 52 ms of delay can be entered with a 1 Hz resolution.

2-26

delay

.

Saving Instrument Setups

Measurement states greatly reduce the time required to set up measurements.

Simply congure the optical spectrum analyzer for any measurement

you repeatedly perform, then save the settings as a measurement state.

Whenever this state is recalled, the previous instrument settings are

automatically restored. Measurement states can be protected from accidental

erasure using the

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

P STATE On Off

softkey.

The optical spectrum analyzer automatically congures to an instrument

Using

state

N

softkey

,

number

a

on.

.

press

you

to

N

save

for the

have

enter

N

preset

create a

can

save

o

T

Press

1.

2.

o

T

numeric

3.

To

the

state whenever

custom power-on

recall

or

left-side

the

measurement

a

store

keypad

recall a

measurement state

front-panel

is

it

a

N

NN

N

State

enter

to

numeric

turned

measurement state

N

state

keypad

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

the

poweron

N

and

,

le name

stored,

le

the

use

.

press

name's

menu

front-panel

N

NN

recall

number

softkey

N

and use

,

.

NNNNNNNNNNNNNN

If you cannot remember the le's number, enter the

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

catalog & MSI

menu to recall the le. Refer to Chapter 13 for

Misc

menu's

information on using the catalog menu.

,

you

2-27

Displaying Signals (Part 2)

To protect measurement state les

1.

Press the left-side

2.

3.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

Press

MORE 1 of 4

Press the

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

P STATE On Off

NNNNNNNNNNNNNNNNN

State

.

softkey.

softkey so that

NNNNNNNN

On

is underlined.

This procedure protects all measurement state les from accidental

front-panel erasure. However, the les can still be erased by some

the

N

MORE

one

NN

N

applications.

power-on

N

left-side

N

of

N

NN

N

1

the

N

IP

N

of

NN

N

State

N

following

N

selects

state

N

NN

softkey

N

4

,

N

MORE

N

.

N

NN

N

and

,

4

of

2

then

N

poweron

NN

N

menu

N

selections:

instrument

the

preset

condition.

restores the last instrument settings before power was

programming

select the

o

T

1.

Press

2.

Press

3.

NN

N



POWERON

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN



POWERON LAST

removed.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN



POWERON RECALL

recalls state-register le 0.

N

.

2-28

Agilent 71450B User Guide

Specifications and Main Features

Frequently Asked Questions

User Manual