ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

5pPAa5. Modeling of optical microphone performance.

Nykolai Bilaniuk

Andre Delage

Inst. for Microstructural Sci., Natl. Res. Council of Canada, Ottawa ON K1A 0R6, Canada

A number of modulation principles and an even larger variety of specific implementations may be considered for all-optical microphones. The procedures for designing optical microphones described in this paper include three principal steps. First the mechanical response of a membrane to an acoustic field is modeled by an analytical technique [A. Hu et al., 3049--3056 (1992)], and is used to obtain the magnitude of the membrane deformation and its frequency response. Next the behavior of the optical path under this flexure is studied using the beam propagation method. Predictions of the optical sensitivity (depth of modulation versus membrane displacement), and optical insertion loss are thus obtained. Third the signal-to-noise performance of the device is evaluated by representing all noise sources as equivalent acoustic noise fields at the microphone input. Applications of this methodology to optical microphone designs under consideration are described.