Daniel, Terry, Nutsinee

While playing with the TTFSS we found that very little s-pol came out of the faraday isolator before going into EOM1 (responsible for laser locking and 35.5MHz modulation for SHG locking). Sticking in a PBS cube we found 6mW of s-pol reflected and ~1W of p-pol transmitted through. We placed a half wave plate to correct for the polarization and mostly s-pol is now going through the EOM. In addition we swapped the EOM to troubleshoot a mystery 780kHz peak and phase dip in the TTFSS transfer function (it was 760kHz for the spare EOM). The peak was a result of the wrong polarization going in. Even with the correct polarization the peak was there but the phase was no longer a dip towards 180deg.

As a result, SHG locking signal needed a sign flipped and the gain needed tweaking at the beginning of the common path.