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 (M2 up to 1100×10-15s3kg-1) and strong optical anisotropy (Δn=0.47) make it possible to design various types of high-performance acousto-optic devices of the middle and far-infrared spectral range. In combination with a wide transparency range (0.62-51µm), the obtained characteristics make the crystal extremely promising in comparison with most existing analogs.