Vitreous As2Se3; Investigation of Acousto-Optical Properties and Application to Infrared Modulator

Acoustic and acousto-optical measurements have been carried out on vitreous As2Se3. Values of acousto-optical figures of merit M (=n6p2/ρ v3) and M′ (=n7p2/ρv) for longitudinal acoustic waves are 1090 × 10−18 sec3/g and 1600 × 10−7 cm2 sec/g, respectively, for He–Ne laser radiation of 1.153 μ polarized along the propagation direction of the acoustic wave. These values are the largest among those for known materials which are transparent in the near-infrared spectral region. Acoustic attenuation has been evaluated as 11 dB/cm at 200 MHz, and the material is considered useful for a modulator element operable up to several hundred MHz. Experimental pulse modulation and transmission of the 1.153-μ laser radiation have been demonstrated using the As2Se3 modulator at an acoustic carrier frequency of 140 MHz. The transmitted pulse pattern has been displayed by the use of TeO2 light deflector.