Indium iodide single crystal: breakthrough material for infrared acousto-optics.

Measurements of the refractive indices and the full set of longitudinal acousto-optical figures of merit in an orthorhombic single-crystal indium iodide (InI) were carried out. The high acousto-optic characteristics ( up to 1100×10) and strong optical anisotropy (=0.47) make it possible to design various types of high-performance acousto-optic devices of the middle and far-infrared spectral range.

Design of far-infrared acousto-optic tunable filter based on backward collinear interaction.

The paper proposes a design of acousto-optic cell applying backward collinear interaction and acoustic mode transformation in a KRS-5 crystal. This cell may serve as an acousto-optic tunable filter for far-infrared spectral range and is able to operate both with collimated optical beams and with divergent beams forming images. The problem of acoustic mode transformation by wave reflection from the crystal facet away from symmetry planes has been solved.