The power requirements for acousto-optic devices increase with wavelength as X2, so it becomes extremely important for infrared operation to have very high figure-of-merit materials available. Potentially important infrared applications include scanners for laser radar, choppers for surveillance satellites, and acousto-optic tunable filters for a variety of systems. Higher efficiency materials are also important as thin films for integrated optic devices, such as the spectrum analyzer, and several bulk acoustic wave-optical waveguide concepts. A large number of materials of the sulfosalt class have been identified as having very desirable acousto-optic properties, and will find use in a number of these applications. More development of these materials is required to make them of suitable quality, and new compositions must be examined to achieve high performance.
G. W. Roland,
"Infrared Acousto-Optic Materials: Applications, Requirements, And Crystal Development," Optical Engineering 19(6), 196901 (1 December 1980). https://doi.org/10.1117/12.7972632