Tektronix OM4006D, User Manual

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Appendix E: Equivalent-Time (ET) oscilloscope operation
Prerequisites.
1. System should be set up and de-skewed following the procedure above.
2. Connect the Reference from Laser 2 to the Reference input with short
PM/APC jumper.
3. Use a standard SM/APC (not PM) fi ber to connect the Laser 1 to the Signal
input.
4. Use the LRCP to set the Signal 1 power level to about 10 dBm to start.
5. Use the LRCP to turn on both lasers and tune them to the same channel where
you will be working. Set the Laser 1 power to get about 100mV pp.
6. Use the LRCP to tune Laser 1 off grid by 100 to 500 MHz.
7. Click Run on the oscilloscope; the data should look like randomly sampled
sine waves.
8. Move the SM fi ber around until you get most signal on RX channels X-I and
X-Q (at least 3:1 ratio between X-I and Y-I. This is most easily done with a
polarization controller).
9. Tape the fi ber down so that you continue to get most signal on X-I and X-Q.
10. Click Single on the oscilloscope.
Procedure to inspect and correct the X-polarization calibration.
1. Use the Optametra OUI to connect to the scope. Record length of ~8000
points recommended.
2. Display the Matlab Engine Window, the X-Constellation Window and the
Y-Constellation Window. Close other windows.
3. Be sure the Constellation Continuous traces is checked (selected) to show
the green curves.
4. Put DispCalEllipsesET in the Matlab Engine Window of the OUI. Delete
everything else in the Matlab Engine Window.
5. Click Run on the OUI.
6. Observe that the ellipses are displayed on the Constellation plots. Right now
only the X-constellation has signal. The green trace should line up with the
blue circle in the X-constellation plot.
136 OM4000D Series Coherent Lightwave Signal Analyzer