Development of a control scheme of homodyne detection for extracting ponderomotive squeezing from a Michelson interferometer

We developed a control scheme of homodyne detection. To operate the homodyne detector as easy as possible, a simple Michelson interferometeris used. Here a motivation that the control scheme of the homodyne detectionis developed is for our future experiment of extracting the ponderomotively squeezed vacuum fluctuations. To obtain the best signalto- noise ratio using the homodyne detection, the homodyne phase should be optimized. The optimization of the homodyne phase is performed by changing a phase of a local oscillatorfor the homodyne detectionfrom a point at which a signal is maximized. In fact, in this experiment, using the developed control scheme, we locked the Michelson interferometerwith the homodyne detector and changed the phase of the local oscillatorfor the homodyne detection. Then, we measured signals quantity changed by changing the phase of the local oscillatorfor the homodyne detection. Here we used the output from the homodyne detectionas the signal.