Synthesis and characterization of chalcogenide glasses from the system Ga–Ge–Sb–S and preparation of a single-mode fiber at 1.55 μm

The aim of this work is to study different compositions in the Ga–Ge–Sb–S system for the definition of two compositions compatible with the elaboration of a single-mode fiber at the 1.55 μm telecom wavelength. The variations of the glass transition temperature (Tg), the dilatation coefficient (α) and the refractive index (n) have been studied for two glasses series: GaxGe25−xSb10S65 (series 1), Ga5Ge25−xSb10S60+x (series 2). This study has lead to the choice of the Ga4Ge21Sb10S65 composition as clad glass for the preparation of the single-mode fiber and Ga5Ge20Sb10S65 composition as the core. The discrepancies for the studied parameters between the core and clad compositions are the following: Δα < 2%, ΔTg < 3% and Δn = 5 × 10−3. Finally a single-mode fiber has been prepared by the rod in tube technique.