haocun.yu@LIGO.ORG - posted 14:41, Tuesday 07 August 2018 - last comment - 08:47, Saturday 18 August 2018(43292)
Optimization of OPO Crystal Position
[Nergis, Sheila, Haocun]
Yesterday we did the measurements for optimizing the OPO crystal position.
Main steps:
- Set a temperature in s step of 1 degree around 33C.
- Move the crystal in a step of 50 or 100 counts (10 for fine adjustments) to achieve dual resonance, and lock the cavity. (E)
- Scanning the seed
- Fine adjust the temperature to maximize non-linear gain.
Green power before the fiber coupler on ISCT6: 18mW
OPO REFL: 7mW
Measurements:
| Temperature (C) | NLG |
| 34.83 | 3.3 |
| 33.85 | 4.8 |
| 32.95 | 5.13 |
| 31.985 | 4.38 |
| 32.4 | 5.28 |
| 32.236 | 4.095 |
The plot with a sinc2 fitting is attached as below, some measurements drop off the fitting, but we have a rough optimized position and temperature for the crystal: ~33 C
From this, we calculated the threshold power is 22mW at the OPO input.
References:
Crystal Translation Stage manual Q521
Lasti ilog Maggie
Plot of NLG vs. Crystal Temperature added.