[Torrey, Sander]

As described in entry 11348, the SHG was found to be producing much less 775 nm light than the SHG spec sheet predicts. We put a half-waveplate in front of the input fibre coupler upstream of the SHG to test the polarisation dependence of the SHG's output power. We found a strong dependence; we optimised the waveplace orientation and found SHG output powers at or slightly above spec.  

We tried to rotate the fibre in the collimator mount to try to send the optimal polarisation to the SHG, but this optimisation process was very laborious and not very succesful (as the fibre collimator mounting is quite finicky), so we decided to leave the half-waveplate in place.