GeS₂-Ga₂S₃-CsI chalcohalide glasses for all-optical switching devices

High-speed all-optical signal routing is achievable by designing new materials with fast response optical nonlinearities (~1ps); in this context, third-order high nonlinear refractive index glasses are the best candidates. In this work, the characterisation of the third-order nonlinear optical properties of a new chalcohalide glass and its application for the fabrication of high-efficiency nonlinear optical devices are presented. We report the measured values of high third-order optical nonlinear refractive index n₂ and the two-photon absorption (TPA) ß (n₂=3.10×10^-5cm²GW^-1; ß=1.45cmGW^-1) of a new ternary GeS₂-Ga₂-CsI chalcohalide glass. Improvements in the glass third-order optical nonlinearity were achieved by the inclusion of Ag-ions in the ternary glass composition. A theoretical analysis of signal propagation along a nonlinear directional coupler (NLDC) in twin-core fibre geometry and the interaction between the signal electromagnetic (e.m.) field and the waveguiding medium were considered in order to estimate the performance of the considered device for all-optical switching applications. All-optical switching, by controlling the optical pulse intensity in NLDC, has been numerically modelled in the second telecommunication window (?=1.31 µm), and preliminary results support the suitability of this glass for these applications.