EXFO PSO-100 Series Optical Sampling Oscilloscopes - Manual (Page 39)

Setting up and Using the Optical Sampling Oscilloscope
Optical Sampling Oscilloscope 31
For the examples in this documentation, we have tested an optical 40 Gb/s
NRZ transmitter, which consists of a laser source modulated by a pattern
generator and a Mach-Zender modulator according to the figure below.
The average input power to the sampling oscilloscope was approximately
15 mW after amplification and filtering. Since the signal sensitivity that is
the peak power required to get 20 dB SNR
, is
approximately 1 mW, you may need to amplify an NRZ signal to measure a
clear eye diagram. Short RZ pulses on the other hand, for example from a
ring laser with comparable average power, and hence high peak power, do
not need amplification. An optical band-pass filter is recommended to filter
out ASE noise from the EDFA. The input signal could, of course, be of
various types of optical amplitude modulated signals at any bit rate from
DC to 1.28 Tb/s or short pulses without data.
Optional 10 GHz clock
Pattern Generator
Laser 1550
nm
Driver
Amplifier
EDFA
Mach-Zender
Modulator Optical
Bandpass Filter
10 GHz clock
40 Gb/s Output
10log
10
P
2
σ
2
⁄ ( ) = ( )