Third-order nonlinear optical properties of the Na2S–PbS–GeS2 sulfide glasses and the Na2S–PbO–GeS2 oxysulfide glasses

The third-order optical nonlinearity of glasses of the Na2S–PbS–GeS2 and Na2S–PbO–GeS2 systems was measured by third-harmonic generation method. The third-order nonlinearities of glasses of both systems increase with the increasing lead content. The maximum value of the third-order optical nonlinearity was 3.00 × 10-12 esu. The addition of PbO basically has little influence on third-order optical nonlinearity, and the largest nonlinearity is 1.49 × 10-12 esu. The minimum appearing at 15 mol% PbO can be explained by the decrease of number density of lead and sulfur. Chemical durability of oxysulfide glasses is superior to that of a pure sulfide system; thus the addition of PbO is important in this sense.