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.