Observation of Acousto-Optic Diffraction of Terahertz Radiation in Liquefied Sulfur Hexafluoride at Room Temperature

Diffraction of terahertz radiation on ultrasound in liquefied sulfur hexafluoride at room temperature was observed for the first time. The dependences of the diffraction efficiency on the sound frequency, angle of incidence, and amplitude of radio-frequency electrical signal applied to a piezo-transducer were studied. Deflection of diffracted radiation by an angle of $\text{10}^\circ$ was observed. It was found that the diffraction efficiency at room temperature is significantly (four times) higher than the one at 14 $^\circ$ C known from the literature. The obtained and published data on the acousto-optic diffraction in liquefied sulfur hexafluoride contradict the well-known theory.