Compositional dependence of the optical properties of new quaternary chalcogenide glasses of Ge–Sb–(S,Te) system

New quaternary telluride glassy materials with composition of GexSb40−xS50Te10 and GexSb40−xS55Te5 (x = 10, 20, and 27) have been synthesized and their optical properties have been studied by means of spectroscopic ellipsometry in the range of 400–820 nm. The optical constants, i.e. the refractive index, extinction coefficient, absorption coefficient, and the optical band gap energy are determined and their compositional dependence is considered. These parameters are characteristics for amorphous structure of the synthesized glasses, revealed from the neutron diffraction measurements.