User`s guide

Agilent 81600B Family Tunable Laser Source Modules and Options Accessories
Agilent 81600B Tunable Laser Source Family, Fourth Edition 27
Option 81600B-072 recommended Option 81600B-072 is highly
recommended over option 81600B-071 to reduce front panel reflections,
which will greatly reduce interference noise and spectral ripple in the test
setup.
NOTE