Ultrafast third-order optical non-linearity of 0.56GeS2–0.24Ga2S3–0.2KX(X = Cl, Br, I) chalcohalide glasses by femtosecond Optical Kerr Effect

0.56GeS2–0.24Ga2S3–0.2KX(X = Cl, Br, I) chalcohalide glasses were prepared and their third-order optical non-linearities χ(3) have been studied systematically using the femtosecond time-resolved Optical Kerr Effect technique at wavelength of 800 nm. In this system, 0.56GeS2–0.24Ga2S3–0.2KCl glass shows the largest χ(3) (1.82 × 10−13 esu), but 0.56GeS2–0.24Ga2S3–0.2KBr glass has the fastest optical non-linear response time in subpicosecond domain (about 340 fs), which is due to the ultrafast distortion of the electron clouds surrounding the balanced position of Ge, Ga, S, K and Br atoms. The local hyperpolarizability determining non-linear optical response are determined by the partially ionic bonds originating from Ge(Ga)–S bonds and halogen valence bonds. They show great potential applications on the glass-based optoelectronic devices like optical switching.