Silicon Micro-machined Optical Microphone Based on Fizeau Interferometry and PGC Demodulation

Fiber-optic microphones have good features of anti-EMI and small size. They can be used in some places where conventional microphones would be hardly applied due to the flexibility of optical fiber. This paper presents theoretical calculations of silicon micro-machined fiber-optic microphone based on Phase-Generated-Carrier (PGC) demodulation, and also develops an experimental optical microphone system using Fizeau interferometer. Experimental results show that this microphone system has high voltage sensitivity, achieving to -12dB at the single frequency of 2 kHz and SNR at 102dB at the same time. The system is of higher precision than traditional capacitive microphone in specific frequency band.