EFFICIENT CW OPERATION OF TUNABLE FLUOROZIRCONATE FIBER LASERS AT WAVELENGTHS PUMPABLE WITH SEMICONDUCTOR-LASER DIODES

Some elements of the rare earths, e.g., Nd3+, Er3+ and Tm3+, show absorption bands situated in the emission range of semiconductor laser diodes. Such pump lasers are naturally interesting for the continuous wave (CW) operation of rare-earth-doped fibre lasers, especially for those emitting in the wavelength range 2-3-mu-m. Their tunability properties are also important for future devices. Results are presented of Nd3+-, Er3+- and Ho3+-doped ZBLAN multi-mode fibre lasers and of Nd3+-doped ZBLAN single-mode fibre lasers with minimum thresholds below 1 mW and maximum slope efficiencies of more than 40%, pumped in the wavelength range 640-890 nm. The tuning ranges achieved using reflection gratings were 38 nm centred around 1050 nm for the Nd3+-doped fibre, 160 nm centred around 2.75-mu-m for the Er3+-doped fibre and 130 nm centred around 2.9-mu-m for the Ho3+-doped fibre.