R&D (FilterCavity)
YuhangZhao - 21:50, Monday 03 September 2018 (970)
Set up EOM of p-pol and corresponding PD

Today I also soildered the Qubig photodiode.(see attached picture 1) According to the specfication, the resonant frequency of EOM is 88.1244MHz. I set up corresponding frequency in the DDS board.(see attached picture 2) Then I did the test of Qubig PD. However I didn't put the PD in the final position. The reason is we don't have the cube BS. If I use plate BS, I will shift beam a little bit and may destory the alignment of OPO. Now Matteo is trying to order it. Hope it will arrive soon.

So I put it at the reflection of PBS, since we have some residual s pol(around 140uW which is luckly a good value for PD) in the p pol beam. I measure this modulation in this perspect. As expected, the level should be low. But we can use this small effect to test EOM and PD. And I found both of them are working well. (see attached picture 3)

COMMENT: I talked with Matteo, he pointed out what I saw should be the comunication between two channels. I checked today that that peak should be the communication. We will do the test after cube BS arrive.

Images attached to this report
970_20180903145000_wechatimg38.jpg 970_20180903145016_wechatimg36.jpg 970_20180903145029_wechatimg37.jpg