[Aritomi, Yuhang, Matteo]

 

This is work on April 17th.

We found that ND 0.4 was attached to a lens in squeezing path. That means we had 60 % loss in squeezing path so far. After we removed it, BAB transmission from OPO before homodyne BS became from 95 uW to 245 uW. We put IR line filter (FL1064-10) in squeezing path to block green going to homodyne. 

 

Then we re-aligned AMC and measured visibility.

power of BAB: 246 uW, LO: 1.2 mW, visibility: 0.7515

Max: 10 V, Min: 1.52 V, mesured visibility: 0.7361

Mode matching: 0.7361/0.7515 = 98%

 

parametric gain

BAB transmission 

without green: 0.16 V

with 52 mW green: 5.24 V

parametric gain: 32.8

 

coherent control

OPO reflection error signal is 111 mVpp. P pol PLL is 135 MHz. 

Though both of CC loops are unstable, we managed to lock both of them. We measured shot noise level at 100 kHz changing demodulation phase of homodyne RF signal. The plot is attached.

 

We also measured shot noise spectrum with squeezing and anti-squeezing. We set demodulation phase 150 deg for squeezing and 10 deg for anti-squeezing. The data and the plot are attached. 

Squeezing angle seems to be stabilized around 100 kHz though there is a large peak at 310 kHz and noise at low frequency.

 

We found that ND 0.4 was attached to a lens in squeezing path. 

That means we had 60% loss in squeezing path so far.We found that ND 0.4 was attached to a lens in squeezing path. 

That means we had 60% loss in squeezing path so far.We found that ND 0.4 was attached to a lens in squeezing path.