Efficient 2.96 μm dysprosium-doped fluoride fibre laser pumped with a Nd:YAG laser operating at 1.3 μm

A quasi-continuous wave Dy3+-doped ZBLAN fibre laser pumped by a ∼1.3 μm Nd:YAG laser and operating at 2.96 μm with an emission linewidth of ∼14 nm (FWHM) has been demonstrated. The 6H 15/2 → 6H9/2, 6F 11/2 absorption band of Dy3+-doped ZBLAN centred at 1.3 μm has been used to pump the 6H13/2 → 6H15/2 laser transition. For a 60 cm fibre length, a threshold of 0.5 W and a slope efficiency of ∼20% with respect to the absorbed pump power was measured. The experimental slope efficiency was ∼45% of the Stokes efficiency limit. The high efficiency relates to low pump ESA losses and an optimised output coupling as compared with previous demonstrations.