In a tunable optoacoustic filter, a portion of the optical fiber is coiled
around and placed at least partially against a rounded shell equipped with
at least one longitudinal slit having an emitter and an absorber on both
sides of the slit in contact with the shell or the optical fiber. The
emitter transmits elastic waves along the shell and therefore along the
fiber to the point of absorber. Coiled configuration of the optical fiber
along with various positions of emitters and absorbers are presented
allowing to widen the functional range of operation of the filter by
increasing the usable length of the optical fiber subject to acoustic
oscillations. As a result a reflection/conversion coefficient of up to
0.999 and the filtration band of 1-10 kHz are obtainable.
