Laser-ultrasonic temperature mapping of an acousto-optic dispersive delay line

Many acousto-optic paratellurite-based devices use a slow shear bulk wave for interaction with light beams. Strong bulk absorption of this wave leads to a significant inhomogeneous crystal heating, a drift of material constants, and to the consequent change in light diffraction patterns. Current paper is focused on a study of thermal regimes in acousto-optic devices. A method of laser ultrasonic time-of-flight thermography of solid-state devices is proposed. The method is used to experimentally evaluate temperature maps of an acousto-optic dispersive delay line with different acoustic pump frequencies. The comparison of obtained results with thermal imaging is carried out, showing good agreement within measurement error.