Fiber-optic microphone based on a combination of Fabry-Perot interferometry and intensity modulation

A fiber-optic microphone based on a combination of Fabry-Perot interferometry and intensity modulation is described. The combination technique eliminates fringe counting ambiguity and provides a wide range of measurement of optical phase change without any complicated electromechanical devices. The experimental data are compared with the result of a theoretical analysis. The microphone has a flat frequency response from 20 Hz to 3 kHz with a high sensitivity of 1.6 rad/Pa. The dynamic range is more than 65 dB. The frequency response and sensitivity can be modulated by changing the size and surface tension of the membrane. The microphone can be easily implemented and can be made very small. © 1995, Acoustical Society of America. All rights reserved