Figure 2

Schematic of the experimental setup implemented to reference the cavity. The stabilized reference laser is transferred to the experimental table through an optical fiber. Labels: QWP quarter waveplate, HWP half waveplate, PBS polarizing beam splitter, ML mode matching lens, HWP half-wave plate, QWP quarter waveplate, BPF premium bandpass filter, M mirror, CCD charge-coupled device, PD photodiode and PMT photomultiplier tube, RFO rf oscillator, LPF low pass filter, PBS1, PBS2 are polarizing beam splitters. The HWP between PBS1 and PBS2 is close to 45 degrees to minimize the probe power fed to the cavity while ensuring that sufficient power of the reference laser reflected by the cavity gets directed to the PD