The third-order optical nonlinearities of Ge-Ga-Sb(In)-S chalcogenide glasses

Research highlights: → It is firstly demonstrated that the nonlinear refractive index n2 is dependent on the covalency of bonds in chalcogenide glass. → Homopolar metallic bonds in chalcogenide glass have positive contribution to large nonlinear refractive index n2 also. → The 80GeS2.20Sb2S3 glass would be expected to be used in the all-optical switches working at 1330 nm and 1550 nm telecommunication wavelengths. -- Abstract: The third-order optical nonlinearities of 80GeS2.(20 - x)Ga2S3.xY2S3 (x = 0, 5, 10, 15, 20 and Y = Sb or In) chalcogenide glasses were investigated utilizing the Z-scan method at the wavelength of 800 nm and their linear optical properties and structure were also studied. By analyzing the compositional dependences and possible influencing factors including the linear refractive index, the concentration of lone electron pairs, the optical bandgap and the amount of weak covalent/homopolar bonds, it indicates that the electronic contribution in weak heteropolar covalent and homopolar metallic bonds is responsible for large nonlinear refractive index n2 in the chalcogenide glasses. These chalcogenide glasses have characteristics of environmentally friendship, wide transparency in the visible region, high nonlinear refractive index n2 and low nonlinear absorption coefficient β, and would be expected to be used in the all-optical switches working at 1330 nm and 1550 nm telecommunication wavelengths.