NAOJ GW Elog Logbook

Recovery of squeezing

[Aritomi, Eleonora, Matteo]

First we checked if the alignment of AMC changes or not from yesterday. For LO, peak is 8.16V and mismatch is 31.2mV+4mV. Alignment got worse from yesterday a bit and it was horizontal misalignment (31.2mV). The mode matching was 99.6%. After alignment, horizontal misalignment became from 31.2mV to 2.4mV. The mode matching is 99.9%.

For BAB, first we maximized OPO transmission of BAB by changing p pol PLL locking frequency. P pol PLL frequency where OPO transmission of BAB is maxmized is 288MHz without green.

Then we injected green and maximized parametric amplification by changing p pol PLL locking frequency. P pol PLL frequency where parametric amplification is maxmized is 174 MHz with 48mW green.

Estimation of parametric gain

Maximum is 6.66V and minimum is 80mV with 48mW green and 308mV without green. So parametric gain is 6.66/0/308 = 21.6, which is consistent with the measurement before.

Estimation of parametric gain

Maximum is 6.66V and minimum is 80mV with 48mW green and 308mV without green. So parametric gain is 6.66/0.308 = 21.6, which is consistent with the measurement before.

For alignment of BAB inside AMC, peak is 240mV and mismatch is 11mV+4mV. The mode match is 94.1%.

Then we measured visibility. Maximum is 8.24V and minimum is 3.84V, which means the visibility is 0.364. Since power of LO is 594uW and BAB is 24uW, expected visibility is 0.386. The mode matching estimated from visibility is 36.4/38.6 = 94%, which is reasonable.

Finally we recovered the squeezing. First attached picture shows shot noise and second attached picture shows squeezing. At 200kHz, squeezing is ~2dB and anti-squeezing is ~11dB.

We'll lock CC and measure squeezing.

First we checked if the alignment of AMC changes or not from yesterday.

For LO, peak is 8.16V and mismatch is 31.2mV+4mV. Alignment got worse from yesterday a bit and it was horizontal misalignment (31.2mV). The mode matching was 99.6%. After alignment, horizontal misalignment became from 31.2mV to 2.4mV. The mode matching is 99.9%.First we checked if the alignment of AMC changes or not from yesterday.