Yenista Optics OSICS, Руководство пользователя

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Using the OSICS T100 Module
OSICS User Manual 193
BKR
TL
S-50
AT
N
DFB
ECL
T10
0
SL
D
SW
T
TLS
-A
G
SW
T
A
PC
MA
IN
13.7.4 Setting Up Analog Modulation Using an External Source
Subject The SMB connector located on the front panel of the T100 module is directly connected
to the laser chip and allows you to couple an external modulating-current to the system
bias current (see Figure 135, p. 184 ).
By modulating this external current, you can modulate the optical power output in a
frequency range from 50 Hz to 50 MHz.
Figure 148: External Analog Modulation Setup
The relationship between the voltage applied at the SMB input and the current added to
the diode is given by: I
in
= V
in
/R
internal
where:
• I
in
is the added current
• V
in
is the voltage applied to the SMB input
• R
internal
is the 50
Ω
internal impedance of your T100 module
TTL modulation can also be applied directly on the module's front panel using the input
SMB connector generally used for the analog modulation. The modulation is applied
directly on the laser chip. In this case, simultaneous modulation for all the modules is not
possible.
Laser diode current level is available in section
OSICS T100 Technical Specifications, p. 173 .
Before Starting Make sure you have a 50 Ω coaxial cable to connect your HF-generator to the 50 Ω input
SMB connector.
Procedure 1. Set the module modulation control to off as follows:
OSICS Module Laser Diode Source
R
internal
50 Ω
Waveform Generator
I
bias
Polarization Current
I
in
I
diode
V
in
Coaxial
cable 50
Ω
Mod.
SMB Connector
50
Ω
Before applying an external analog-modulation, make sure the
modulation control is set to off.
CAUTION