3. Operation
A typical application of the
FSC
is to frequency-lock a laser to an
optical cavity using the
PDH
technique, as shown in figure 3.1. The
cavity acts as a frequency discriminator, and the
FSC
keeps the la-
ser on resonance with the cavity by controlling the laser piezo and
current through its
SLOW
and
FAST
outputs, reducing the laser line-
width. A separate application note (
AN002
) is available that provides
practical advice on implementing a
PDH
apparatus.
TRIG
CH1
Serial:
TRIG
FAST OUT SLOW OUT
MOD IN
POWER B
POWER A
MONITOR 1
MONITOR 2
SWEEP IN
GAIN IN
B IN
A IN
LOCK IN
Laser
EOM
Cavity
PBS
LPF
PD
Piezo
Current
Oscilloscope
AC
CH2
Figure 3.1:
Simplified schematic for
PDH
-cavity locking using the
FSC
.
An electro-optic modulator (
EOM
) generates sidebands, which interact with
the cavity, generating reflections that are measured on the photodetector
(PD). Demodulating the photodetector signal produces a
PDH
error signal.
A variety of other methods can be used to generate error signals,
which will not be discussed here. The rest of this chapter describes
how to achieve a lock once an error signal has been generated.
19
Summary of Contents for FSC100
Page 1: ...Fast servo controller FSC100 Version 0 1 2 Rev 2 4 hardware ...
Page 4: ...ii Contents ...
Page 14: ...10 Chapter 1 Introduction ...
Page 22: ...18 Chapter 2 Connections and controls ...
Page 36: ...32 Appendix B 115 230 V conversion ...
Page 39: ......
