Improved nonlinear optical properties of chalcogenide glasses in Ge-Sn-Se ternary system by thermal treatment

Abstract

In this work, a series of chalcogenide glass ceramics were prepared by thermal treating a precursor glass in molar composition of Ge20Sn5Se75 with different duration. X-ray powder diffraction (XRD) measurements showed the precipitation of nano-crystals belonging to GeSe2 and SnSe2 phases in the heat-treated glasses, which was confirmed by Raman spectra as well. The crystallization in glass matrix caused the variation of optical properties (i.e. Optical band gap, Urbach energy) due to localized field effect of the nano-crystals, while the infrared transmittance was kept unchanged. Third-order optical nonlinear properties of the precursor glass and glass ceramic samples were investigated by femtosecond Z-scan technique at telecom wavelength of 1550 nm. The maximum nonlinear refraction (γ) of the Ge-Sn-Se glass ceramics reached 5.319 × 10−16 m2/W, which is almost one order higher than that of the precursor glass, demonstrating the significant influence of nano-crystals on optical nonlinear property of the chalcogenide glasses.