Study on the structure dependent ultrafast third-order optical nonlinearity of GeS2–In2S3 chalcogenide glasses

The results of the femtosecond time-resolved optical Kerr at 820 nm in GeS2–In2S3 chalcogenide glasses indicate that the response time in GeS2–In2S3 glasses is subpicosecond, which is predominantly due to the distortion of the electron cloud. The value of χ(3) in 0.95GeS2–0.05In2S3 glass is also as large as 2.7 × 10−13 esu, and it reduces with the addition of In2S3, which may be ascribed to the microstructure evolution of GeS2–In2S3 glasses. It is deduced that the intrinsic [Ge(In)S4] tetrahedral structure units that possess the high hyperpolarizability may do great contribution to the enhancement of third-order optical nonlinearity while [S3Ge–GeS3] ethane-like molecular units make no considerable contribution to that in femtosecond time scale. These GeS2–In2S3 and GeS2–In2S3-based chalcogenide glasses would be expected to be the promising materials for all-optical switching devices.