nutsinee.kijbunchoo@LIGO.ORG - posted 16:47, Wednesday 21 February 2024 - last comment - 12:42, Friday 23 February 2024(75919)
SHG crystal temperature sweep
I just ran a script that sweeps SHG crystal temperature. This test requires TTFSS, PMC, and SHG locked. PLEASE DO NOT TOUCH THE SQUEEZER. PLEASE WALK GENTLY NEAR SQZT0. The duration of the script is ~2hrs. Star time is 16:40.
The script sets the crystal temperature from 29C - 41C at 0.5C increment. We hope to replicate the phase matching curve done by a SURF student Nathan Zhao (P1400193 Fig 23). The script can be found in /opt/rtcds/userapps/trunk/sqz/h1/scripts/SHGphasematch.py
Here's our Sinc function. Not sure what's going on with the dip in the middle but I believe we have been operating at a good place (the right peak, ~36C). Although after the temperature scan the green production didn't come back to where it started. I moved the crystal temperature to the middle of the sinc function to confirm that the conversion efficiency really went down. I then moved the crystal temperature to the left peak of the sinc function (~34 C) and managed to recover 10mW of green.
Something else is drifting as well and it seems to have nothing to do with me. PMC PZT ran out of range this morning so I expanded the scan range down to 0V temporary (the current lock triggered at ~25 V). SHG PZT is still drifitng as I'm writing this alog while the green conversion goes down with it. For now I decidede to park the crystal temperature at 33.78C. Changes accepted in the SDF.
Attached a plot with SHG red transmission.