Correlation between acousto-optic and structural properties of Ge–Sb–S chalcogenide glasses

The acousto-optic properties of (100–x)GeS2-xSb2S3 (with x = 70, 60, 50, 40, 30, 20 mol%) and Ge12SbyS88-y (with y = 32, 25, 18 mol%) glasses were investigated, as well as the thermal and mechanical properties. The effects of Sb2S3 and Sb introduction on the structure and above-mentioned properties were discussed. For the first series of glasses: (100–x)GeS2-xSb2S3, the progressive introduction of Sb2S3 decreased the number of GeS4 units in the glass network. Consequently, the Vickers hardness, elastic modulus and stability of the glass against crystallization decreased dramatically. Increased acousto-optic figure of merit and increased acoustic attenuation were also observed. By contrast, for the second series of glasses Ge12SbyS88-y, some new long-chain structures were generated in addition to the increased SbS3 trigonal pyramid units in the glass networks with increased Sb content, which led to the opposite trend of the above performance except that the figure of merit increased. The maximum value with respect to the highest figure of merit was 252 × 10−18 s3/g obtained in Ge12Sb32S56 at 1550 nm and the corresponding acoustic attenuation was 1.95 dB/cm at 25 MHz ultrasonic frequency.