Daniel, Nutsinee

The OPO is now locked to pump laser/PSL beat note with beat note error signal (from TTFSS preamp) goes to input of the OPO common mode board and 158MHz to common mode board LO. We bypassed the PZT driver box completely to reduce the gain to the OPO PZT (PZT driver box has a gain of x22, and a pole at 400Hz). 10Hz low pass filter was added between OPO common mode board output and in-vac PZT driver to give it a low frequency roll-off, which (according to the sketchy writing on the box) attenuated the signal by a gain of 10. Haven't looked at the spectrum or transfer function (will add that to the comment later). A stable beat note frequency is needed for 3MHz locking (with PSL being an LO).

Problem: It will lock +-50kHz sideband instead of 0Hz beat note frequency. Next step is to try using a PFD instead of an IQ demod.