Investigation of the Ga-Sb-S chalcogenide glass with low thermo-optic coefficient as an acousto-optic material

In this study, two series of Ga_xSb_40-xS₆₀ (x = 4, 6, 8, 10 mol%) and Ga_ySb₃₆S_64-y (y = 3, 5, 6 mol%) glasses were prepared and the relationship between their compositional and acousto-optic (AO) properties was investigated systematically for the first time. In the Ga_ySb₃₆S_64-y system, the AO figure of merit (M₂) increased as the Ga increased, and the maximum M₂ of the Ga₆Sb₃₆S₅₈ glass was 455.78 × 10^?18 s³/g, which is ～301 times greater than that of fused silica and ～2.5 times greater than that of As₂S₃ chalcogenide (ChG) glass at 1550 nm. However, its thermo-optic coefficients (dn/dT) varied greatly (32.1 × 10^?6 °C^?1–57.2 × 10^?6 °C^?1), and acoustic attenuations (α) at 10 MHz were high, from 5.446 dB/cm to 7.274 dB/cm. In the Ga_xSb_40-xS₆₀ glass system, the M₂ value and α at different ultrasonic frequencies gradually decreased with the improvement of Ga. Compared with the Ga_ySb₃₆S_64-y system, the Ga_xSb_40-xS₆₀ glass system had lower α (at 10 MHz) and dn/dT, which are 5.001 dB/cm–5.563 dB/cm and 17.3 × 10^?6 °C^?1–55.6 × 10^?6 °C^?1, respectively. These results provide a significant reference for the further development of novel ChG glasses and help expand their application fields.