Optical amplifiers and lasers in infrared fibres

We are currently investigating two infrared glasses for active applications. Gallium lanthanum sulphide (GLS) glass is investigated as a potential host material for rare-earth doped mid-infrared fibre lasers. We have fabricated gallium lanthanum sulphide glass by melt quenching and drawn into fibres using the rod-in-tube technique. Fluoroaluminate glasses (ALF) are being prepared in planar form by spin coating and clad waveguides have been achieved. The quality of waveguides from both these materials is gradually being improved as methods to eliminate transitions metals and other impurities, understand crystallization and reduce imperfections at the core/clad interface are developed. Although initially motivated by the demand for a practical 1310nm amplifier, interest has now extended further into the infrared. We describe recent progress in these glasses, their properties and applications.