Reduction of optical nonlinearities of Ga-La-S glasses for active fibre applications through addition of CsCl

Measurements of the optical nonlinearities of halide modified GaLa sulphide glasses near 1.3µm are reported. The addition of CsCl to the glass matrix reduces the intensity-dependent index of refraction by up to an order of magnitude, making these glasses better candidates for fibre amplifiers than pure Ga-La sulphide glass.