Modes of wide-aperture acousto-optic diffraction in a uniaxial birefringent crystal

Abstract

Acousto-optic (AO) anisotropic interaction in uniaxial birefringent crystals is a widespread and versatile approach to tunable spectral filtration of light. Its principal constraints are limited values of spectral and angular bandwidth restricting the light transmission and imaging performance of AO filters. A way to overcome these drawbacks is simultaneous Bragg diffraction of two or more light beams. In this paper, we discuss and compare the main features of four available modes of anisotropic wide-aperture AO interactions in uniaxial birefringent crystals. We calculate the angular aperture, spectral resolution and other parameters and estimate the spectral image quality features related to each one. Theoretical consideration and computational modeling are carried out for tellurium dioxide (TeO2)—the main AO crystal. Derived results are important for the development of AO imaging devices, particularly multi-channel AO tunable filters.