Nutsinee Marc Daniel

This is a characterization of the intensity noise stabilization servos for the OPO pump and the CLF beam. During these measurements the OPO was locked with 690nW in transmission, whereas CLF photodetector in reflection showed 120µW of light.

The first plot shows the transfer function of the OPO ISS. The configuration was 31dB gain, positive sign, 40/2kHz boost, setpoint at -2.5V, and the control at 7.4V. The ugf is about 20kHz.

The second plot shows the transfger function of the CLF ISS. The configuration was 16dB gain, negative sign, 40/2kHz boost, setpoint at 1.010V, and the control at 5.83V. The ugf is about 15 kHz. Some gain peaking is visible.

The third plot shows the relative intensity noise on the OPO TRANS photodetector with the ISS on and off. We reach shot noise limited performance everywhere >10Hz. Not sure what the excess noise is at low frequencies.

The forth plot shows the relative intensity noise on the CLF REFL photodetector with the CLF ISS on and off, while the OPO ISS is on.

The fifth plot shows the relative voltage noise on the CLF I channel (we lock on Q) with the ISS on and off. This signal doesn't seem to care about the ISS.