User`s guide

Optional Performance Tests Performance Tests
Agilent 81600B Tunable Laser Source Family, Fourth Edition 137
Test Setup and Measurement Procedure
General Remarks The idea behind the measurement procedure described in this section is to
characterize only the performance penalty in the wavelength
measurements of the tunable laser when replacing the traditional stepped
operation with continuous sweeps. The derivation of the total wavelength
uncertainty under swept operation (as described in the Definition of Terms)
is described later, in the corresponding Analysis sections of each term.
The transmission peaks of a stable Fabry-Perot etalon are used as control
points to compare the measurement performance of the TLS in the two
operating conditions; in particular, the wavelength at which a relative
threshold is crossed. The threshold is positioned at 2 dB below the
maximum transmitted power of each peak, to ensure a local slope of
~
0.33
dB/pm.
For this reason, the measurements described here should not last more
than approximately 15 minutes, timed from the reference measurement to
the last of the verification measurements. This relaxes the stability
requirements on the etalon used as a relative reference. It also avoids
unnecessary characterization of long-term drifts that are already
accounted for in the specifications given for stepped mode. This
requirement is easily satisfied when executing the measurements using
the Plug and Play drivers, which are anyway required also for other
reasons; however it imposes particular optimizations in the execution of
the reference measurement.
It is also crucial to connect all cables only once: avoid repeating or
(un)tightening the connections during or between these measurement
Measurement
Sequence
1 Make sure that cable connectors, detectors and adapters are clean.
2 Connect the equipment as shown in Figure 42.
Figure 42 Setup for wavelength uncertainty verification in swept mode
3 Turn the instruments on and allow the instruments to warm up for at
least 60 minutes.
4 Move to the TLS channel of the 8164A/B mainframe. Set the [Menu]
parameters to: