Sacher Lasertechnik
Group
User Manual Laser Diode Controller PilotPC 32
Current Coupling Setup
Theory of operation.
Most tunable external cavity diode lasers are fine-tuned electrically with
a piezo actuator. Providing a coupling between the piezo voltage and
the injection current results in a large enhancement of the modehop-free
tuning range of external cavity diode lasers.
The laser driver of Sacher Lasertechnik provides an adjustable coupling
between the piezo voltage and the injection current of the diode laser.
Therefore, the modehop-free tuning range of our Laser systems may be
enhanced by a factor of up to 5. For example, if theoretical modehop-
free tuning range is limited to 10GHz, then the modehop-free tuning
range may be increased up to 50GHz with Current Coupling.
Current coupling Block diagram
In case of I-Mode the laser current will turn up as follows
When direction is POS
Laser current = Laser Current Set + Piezo Voltage x Gain
When direction is NEG
Laser current = Laser Current Set - Piezo Voltage x Gain
Prescaler Direction
control
Amplification
Laser diode
current source
+
Laserdiode Current
Setpoint
Piezo Input
Gain
Direction Enable Amplification
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