Using the OSICS T100 Module
182
OSICS User Manual
13.5
Activating Coherence Control
Subject
The Coherence Control function induces broadening of the OSICS T100 tunable laser
linewidth. This feature is especially useful in helping reduce interferometric noise.
Coherence control consists in modulating the frequency with a pseudo-noise signal that
widens the OSICS T100 optical signal linewidth. The specified linewidth for the OSICS
T100 module is 150 kHz (typical value) as indicated in the module specifications without
coherence control. This linewidth is brought to 100 MHz when the coherence control
function is on.
The OSICS T100 module features a built-in modulation source used to implement
coherence control function on-board. You do not need to connect any external
modulation device to the OSICS system.
The following procedure explains how to activate the coherence control function to
produce the linewidth broadening required.
Procedure
1.
Access the T100
Unit Setup
menu (see section
Accessing an OSICS Module Setup
).
2.
Turn the rotary knob to put the cursor before the
Coherence
menu and press the
knob.
The
Coherence
menu appears and the cursor points to the current setting.
Figure 133: T100 Unit Setup – Coherence Control menu
3.
Turn the rotary knob to put the cursor before the wanted setting, and press it to
validate your selection.
The new state of the coherence control function is implemented immediately. The
Unit Setup
menu is automatically displayed.
In the OSICS
System Status
screen, the message
C
is displayed in the OSICS module
channel
Info
field if the coherence control function is currently enabled on this
module.
Main
EXIT
1
2
3
4
5
6
7
8
Unit Setup - Coherence
ESCAPE
▲
Coherence :
OFF
ON
Select a new value.
