Composition dependence of thermally induced second-harmonic generation in chalcohalide glasses

By investigating the second-harmonic generation (SHG) of the series (100 − 2x)GeS₂·xGa₂S₃·xPbI₂ (x = 5, 10, 15, and 20) chalcohalide glass samples after thermal poling, it was found that there was an optimal poling temperature for each composition and there was also a relation between optimal poling temperature and glass transition temperature. With increasing x, the obtained second-order susceptibility χ⁽²⁾ shows an increase first and then decrease, and the maximum was seen at x = 15. A dipole reorientation model and structural relaxation causing by Ga₂S₃ and PbI₂ were proposed to explain the dependence of poling temperature on SH intensity for each composition and the presence of the maximum χ⁽²⁾ in this chalcohalide glass series.