Impact of thickness on nonlinear absorption properties of chalcogenide glasses Ge28Sb12Se60 thin films

Chalcogenide glasses exhibit high optical nonlinearity and are widely used in developing various optical modulating devices. Due to the influence of coating processes and the properties of the glass material, the film thickness is one of the factors affecting the optical nonlinear coefficient of chalcogenide glass thin films. This paper presents the nonlinear optical characterization of chalcogenide glass Ge₁₂Sb₂₈Se₆₀ thin films of various thicknesses. The measurements were conducted using the Z-scan method and the pump-probe method at a wavelength of 532 nm. The results demonstrated that as the film thickness increased from 25 nm to 200 nm, the nonlinear absorption of the material decreased from 1.1 × 10^-6 m/W to 0.68 × 10^-6 m/W. This trend will become more gradual as the film thickness increased. This means that the chalcogenide glass on the surface of the film has greater optical nonlinearity.