Thermal and optical properties of chalcohalide glass

We report on the use of cw time-resolved Z-scan technique to investigate the thermal nonlinearity for the (mol%) 40% PbI2 – 30% Sb2S3 – 30% As2S3 chalcohalide glass. Transient measurements were made with the sample fixed at the peak position of the Z-scan curve, which is equivalent to the single beam thermal lens (TL) configuration. The response time of the transient signal was used to obtain the sample thermal diffusivity, D=1.3×10−3 cm2 s−1. The signal amplitude is proportional to the optical path length change with the heat deposited per unit volume, ds/dQ. The measurements were performed using a tunable Ti:sapphire laser in order to investigate the wavelength dependence in the range from 730 to 840 nm. This range is close to the glass Urbach tail, at λ∼700 nm, where ds/dT (or ds/dQ) increases. We observed that ds/dT increases by a factor of 9.3 when the wavelength decreases from 840 to 730 nm, while the absorption coefficient increases by a factor of 1.7.