NAOJ GW Elog Logbook 3.2
[Aritomi, Eleonora, Yuhang]
First we measured locking accuracy as shown in FIG. 1. Locking accuracy is 8 Hz which corresponds to 8.8 pm.
Then we changed green pump power from 50mW to 40mW so that we can reproduce FDS measurement before. OPO temperature and p pol PLL is as follows.
| green power (mW) | 0 | 40 |
| OPO temperature (kOhm) | 7.2 | 7.2 |
| p pol PLL (MHz) | 300 | 190 |
Then we measured FDS around 400 Hz and 75 Hz detuning (FIG. 2 and FIG. 3). The parameters are as follows. Degradation budget is shown in FIG. 4.
It seems that locking accuracy is limiting squeezing level at low frequency.
sqz_dB = 16; % produced SQZ
L_rt = 150e-6; % FC losses
L_inj = 0.20; % Injection losses
L_ro = 0.11; % Readout losses
A0 = 0.05; % Squeezed field/filter cavity mode mismatch losses
C0 = 0.05; % Squeezed field/local oscillator mode mismatch losses
ERR_L = 8.8e-12; % Lock accuracy [m]
ERR_csi = 80e-3; % Phase noise[rad]
phi_Hom = [-4/180*pi, -27/180*pi]; % Homodyne angle [rad]
det = [423 446]; % detuning frequency [Hz]
sqz_dB = 16; % produced SQZ
L_rt = 150e-6; % FC losses
L_inj = 0.20; % Injection losses
L_ro = 0.11; % Readout losses
A0 = 0.05; % Squeezed field/filter cavity mode mismatch losses
C0 = 0.05; % Squeezed field/local oscillator mode mismatch losses
ERR_L = 8.8e-12; % Lock accuracy [m]
ERR_csi = 80e-3; % Phase noise[rad]
phi_Hom = 90/180*pi; % Homodyne angle [rad]
det = 75; % detuning frequency [Hz]
Given the number Aritomi-san used (which are maybe too optimistic about MM), if we reduce the amount of initial squeezing from 16 dB to 6 dB. The effect of lock accuracy is much reduced and in priciple we should be able to go below shot noise.
