Agilent Technologies 86038B User Manual page 295

If the Wavelength Correction does not complete
N O TE
If Mode Hops are reported in the Status Bar
Agilent 86038B Photonic Dispersion and Loss Analyzer, Second Edition
Only applies if 86122A is installed
The wavelength correction will not complete if there is a low or
missing signal.
1 Ensure that the test set power cord is plugged in.
2 Ensure that the MWM is plugged in and turned on. The
MWMs GPIB cable should be attached to the rear of the PNA
and have a GPIB address set to 10. If any of the above
conditions are not met, correct the setup and then exit the
PDLA software (File > Exit > Yes) and restart. The PDLA
software will detect the MWM on power up, or by selecting
Preset.
3 Make sure that there is a short patch fiber running from the
Low SSE output of the TLS to the input on the MWM.
4 Look at the status area of the MWM to ensure that there are
no errors displayed. If there are errors, refer to the MWM
online Help.
Mode hops (small sudden shifts of the laser wavelength) can
occur swept-mode measurements for wide wavelength ranges,
some wavelength ranges near the end of the tunable laser range
and for low laser power settings. Even when this occurs, the
tunable laser wavelength is accurately determined at the trigger
for each measurement sample. However since the swept
measurement samples are integrated over the time between
samples, the mode hop can influence some results. A typical
result is a spike in the DGD data.
The 86038B records and reports the occurrence of any such
mode hops. If one occurs during a sweep, the sweep is
automatically repeated. If it occurs again, then it is assumed to
be unavoidable and the measurement will be completed with a
report of the mode hops. This report can be used to clarify that
bad measurement points at these wavelengths are not due to
device under test.
Please refer to the tunable laser specifications for the conditions
under which mode-hop free continuous sweeps are specified.
295