Nutsinee Terry Daniel

Today we tried to lock the OPO in green. First, we swapped the busted 1801 with a BBPD and realigned it. The RF signal is quite large and we ended up installing a 20dB attenuator in the green EOM modulation path. As expected the green transmitted power is tiny, about 70nA when locked with ~1.3mW. We suffered from red contamination until we turned the seed off. We probably need a second dichroic beamsplitter in this path.

We first tried to lock the laser to the OPO, but soon realized that this won't work with 1MHz of VCO range. We switched to the OPO PZT and were able to keep it "locked" near resonance within about the full width. What remains looks like a ~1kHz feature that we can't suppress, since at higher gain setting we see an instability around 5kHz. The dip in reflection seems to be about ~0.7.