Non-linear effects in chalcogenide glasses

Abstract

ABSTRACT Femtosecond filamentation of 800 nm laser pulses in the co nditions of strong two-photon absorption was first directly observed in As 4 Ge 30 S 66 chalcogenide glass. In this paper we also present the experimental results on laser self-written waveguides in arsenic-germanium-sulfide glasses. In contrast, there was no filamentation and spectrum widening in stoichiometric As 2 S 3 glass. It was shown that nonlinear figure of merit was as high as 0.52 and only 0.04 in glassy As 4 Ge 30 S 66 and As 2 S 3 , respectively. KeyWords: Chalcogenide glasses, two-photon absorption, Kerr effect, filamentation, self-writing waveguides I. INTRODUCTION Chalcogenide glasses (ChG), based on the group IV chalcogen elements sulfur (S), selenium (Se) and tellurium (Te), and are of the significant interest to photonics and optoelectronics. These glasses stand out for their unusually ultra-fast non-linear optical response. Chalcogenide glasses offer a numbe r of significant advantages in respect with silicon as a non-linear material, such as: 1) High optical transparency in the near IR as well as into the far IR regions; 2) Photosensitivity to the band gap light action which has been used for writing both for channel waveguides and diffractive periodic structures; 3) High refractive index (n=2 y 3), that allow tight bending radius as well complete band gaps to be engineered in photonic crystal structures; 4) Large third order nonlinearities, with the reported of high values for the nonlinear refractive index for As