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R&D (FilterCavity)
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ChienMingWu - 02:05, Wednesday 02 August 2023 (3307)Get code to link to this report
Measured FIS of 5.4 dB at 25mW and 5.7dB at 40mW green power

8/1 [Chien-Ming and Hsun-Chung]

We measured around 5.4dB squeezing and 11.4dB antisqueezing at 25mW green pumped,
                             and 5.7dB squeezing and 16.7dB antisqueezing at 40mW green pumped.

Without green pump, OPO T=7.107 kOhm; BAB=192mV, p-pol PLL: 225MHz
At 25mW pump, OPO T=7.118 kOhm; BAB max=1.27V, min=80mV, p-pol PLL:165MHz
Nonlinear gain=6.61

At 40mW pump, OPO T=7.120 kOhm; 
BAB max=3.28V, min=40mV, p-pol PLL:130MHz
Nonlinear gain=17.08

The SHG power in front of MZ drops to
151.5mW today.
In addition, we found the LO power to HOM also drops to 1.68mW. We can't increase it by alignment, so we have to replace the 
OD0.3 ND filter before IRMC to OD0.1.
As a result, the LO power is restored to 1.94mW.
We suspect that the output power of the main laser may be continuously decaying, causing the SHG and LO power to drop!


Attached are two squeezing measurement at different pump powers. It is worth mentioning that when the HOM DC cable is too close to the oscilloscope, some noise peaks will appear obviously, especially on dark noise.
The units setting parameters of SR785 was also attached.

Images attached to this report
3307_20230801185323_230801sq25mw.png 3307_20230801185342_230801sq40mw.png 3307_20230801185521_sr785unitssetting.jpg