Optoacoustic frequency filter

The present invention relates to the field of fiberoptics and more specifically to the tunable filters for optical fibers and can be used for construction of wavelength-selective optical devices, based in particular on optoacoustic effect, with tunable spectral range of reflected (transmitted) electromagnetic waves. 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.