Atec MS9720A User Manual

High-Performance
WDM Measurement

MS9720A

WDM Network Tester

2

±

20 pm Wavelength Accuracy with Built-in Light Source

■ ±20 pm Wavelength Accuracy (Reference Optical Source Built-in)

■ 58 dB Dynamic Range (1 nm from Signal Wavelength)

■ –87 dBm Optical Reception Sensitivity

■ Three Memories, Three Traces, Split Screen

■ Full Line-up of Functions and Applications

■ VGA Output Connector

The MS9720A is an optical spectrum analyzer with a
diffraction grating that is used to measure and analyze optical spectra in the 1450 to
1650 nm band for WDM communications systems.
In addition to having excellent basic performance such as high wavelength accuracy,
wide dynamic range and good optical reception sensitivity ideally suited to measurement
and analysis of the optical spectra used in WDM communications,it also has a full line-up
of functions matching a wide range of needs ranging from manufacturing of WDM
communications devices,to installation and maintenance.

A wavelength accuracy of ±20 pm is achieved over a range
of 1530 to 1570 nm by performing calibration using the built­in wavelength reference light source. Wavelength calibration
is performed automatically just by pressing the Cal key, per­mitting accurate measurement of the absolute wavelength
value required in evaluation of WDM systems. Calibration of
the absolute wavelength value uses the absorption spec­trum of acetylene. The block diagram of the calibration light
source is shown below. In addition, the output of the built-in
SLD light source can be used for ev aluating the transmission
characteristics of passive elements

Three Memories,Three Traces, Split Screen

Up to three memories can be used for measurement; the
results found by mathematically processing the data in these
three memories can be displayed as up to three traces on
the screen. Furthermore, by using the split screen function,
it is possible to simultaneously display two sets of measure­ment data on the screen as well as the difference between
the two sets of data.
The following screen shows a measurement of filter charac­teristics; the top half of the split screen shows the reference
light and the measured optical spectrum while the bottom
half shows the spectrum of the measured light minus the
reference light.

Measure­ment
section

SLD optical
output

Optical input

SLD light
source

Acetylene
absorption cell

Optical
switch

Block Diagram of Calibration Light Sourc

Ideal for High-Performance WDM Measurement

From R&D and production to installation and maintenance of
WDM communications devices

3

58 dB Dynamic Range

The measurement dynamic range at the wavelength 1 nm
from the peak is 58 dB demonstrating the tester’s power
when measuring the SNR of light sources in WDM systems
and when evaluating filters, etc.The following screens show
the dynamic range at 1 and 0.5 nm from the peak.

–87 dBm Optical Reception Sensitivity

The MS9720A noise level is –87 dBm, so the tester is ideal
for measuring the SNR of light sources used in WDM sys­tems, as well as optical leakage and reflected light.The fol­lowing screen shows a measurement of an optical spectrum
of a DFB LD with the output level attenuated to –85 dBm at
a VBW of 10 Hz.

The SNR is improved by using averaging processing. The
following is an example of measurement result after 10
sweep averaging are performed.

Dynamic range

58 dB (1 nm from peak)
53 dB (0.5 nm from peak)

4

Full Line-up of Functions and Applications

In addition to its excellent basic performance, the MS9720A
has a full line-up of useful functions. The basic waveform
analysis functions offer applications for evaluating every
important item in WDM systems.

The following screens show threshold and SNR analysis of
a WDM signal waveform. The effective analysis range is set
using the Zone Marker even f or WDM signals , enab ling inde­pendent analysis of the waveform of each channel.

Insertion Loss Measurement

At insertion loss measurement, the inser tion loss of optical
devices such as optical couplers can be measured.The fol­lowing screen shows a measurement of the transmission
characteristics of a band pass filter.

In addition, the measurement results for a specified WDM
channel wavelength can be displayed as a list.

The following diagrams show the setup when measuring the
insertion loss of a WDM coupler using the built-in SLD , or an
external light source.

Reference Measurement

Waveform
analysis

Applicable
measurement

Threshold analysis, SMSR analysis, spec­trum power (integrated power calculation)

Insertion loss, isolation, directivity, return
loss, polarized mode dispersion (PMD), fiber
amplifier noise figure (NF), WDM wavelength
analysis, long-term measurement

Externallight

COM

Tx1
Rx2
Tx3

Rx4
Tx5

Rx6
Tx7

Rx8

MS9720A