Optimisation of a two colour pumped Tm3+-doped ZBLAN fibre amplifier at 1.49m

Abstract

The authors have constructed a 4 metre length thulium-doped ZBLAN fibre amplifier optically pumped at 0.8 mm by a tuneable Ti : Sapphire and at 1.06 mm by an Nd3? :YAG laser. The authors obtained 12.5 dB for small-signal gain at 60 mW for the two pumps? optical power. The behaviour of the amplifier has been analysed with the optical power of the signal approaching the saturation condition (25 dBm) and at different wavelengths for the Ti : Sapphire pump laser. A model was developed for the optimisation of the amplifier for signal power below the saturation intensity at wavelengths between 1.49 and 1.53 mm (S-band). This shows an empirical quadratic dependence of the Nd3? :YAG power with respect to the Ti : Sapphire power in order to obtain the maximum photon conversion efficiency making the optimised amplifier employable as a booster amplifier in the supporting telecommunication band.