Feedback Controlyzer DigiLock 110
Page 62
Status: 5.12.17
10.3 Pound-Drewer-Hall Stabilization to a Cavity
The second important application described here is the stabilization of a laser to a cavity with the Pound-
Drever-Hall technique. Figure 52 shows an overview of the setup used for a Pound-Drever-Hall stabiliza-
tion onto a cavity in reflection. In this example the cavity is a FPI 100 Fabry-Perot interferometer, available
from T
OPTICA Photonics AG.
Figure 52 Experimental setup of a Pound-Drewer-Hall (PDH) stabilization to a cavity.
Note that the modulation is directly added to the <Main out> channel of the DigiLock 110.
Alternatively the modulation can be applied to the mod AC input of the DLpro.
The initial setup is the same as in the other examples, see section 10.1 steps 1 to 12. Once the spectros-
copy signal is obtained, the following steps are analogous to the case of the Doppler-free absorption
spectroscopy, see section 10.2 steps 13 and 14. Figure 54 shows the expected signal for scanning across
a resonance of the cavity. It can directly be used for side of fringe locking analogous to section 10.2.1.
15a. To generate the error signal for locking to the maximum of the resonance use the PDH module. The
PDH module provides a number of higher modulation frequencies in the MHz range. In the case of
the cavity with well separated modes, modulation frequencies much larger than the characteris-
tic linewidth combine steep slopes with a large capture range.
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