Fig. 1. Block diagram of resonance frequency measurement of RPD

Fig. 2. Layout of the LC resonant circuit and its equivalent circuit. (a) LC resonant circuit; (b) equivalent circuit

Fig. 3. Circuit diagram of resonant photodetector

Fig. 4. Experimental device for measuring the transfer function of photodetector and error signal for servo control system

Fig. 5. Gain comparison of BPD and RPD that has a resonant frequency of 20 MHz and a 3 dB bandwidth of 0.285 MHz

Fig. 6. Comparison of error signals for cavity-locking of RPD and BPD. (a) RPD; (b) BPD

Fig. 7. Comparison of signal-to-noise ratio of BPD and RPD error signals