Investigation of a 791-nm pulsed-pumped 2.7-μm Er-doped ZBLAN fibre laser

A pulsed Er 3+-doped ZBLAN fibre laser with 1.9 mJ of output energy at 2.7 μm in near transverse-single-mode operation is reported. A maximum slope efficiency of 13.5% with respect to launched pump energy at 791 nm was determined. The laser line shifts to a longer wavelength at the end of the output pulse because of reabsorption losses from the lower laser level at shorter wavelengths. The temporal behaviour of the laser output cannot be explained by the common rate-equation models. Possible quenching processes of the pump level are discussed.