We report the highest power operation of a resonantly cladding-pumped, holmium-doped silica fibre laser. The cladding pumped all-glass fibre utilises a fluorine doped glass layer to provide low loss cladding guidance of the 1.95 µm pump radiation. The operation of both single mode and large-mode area fibre lasers was demonstrated, with up to 140 W of output power achieved. A slope efficiency of 59% versus launched pump power was demonstrated. The free running emission was measured to be 2.12-2.15 µm demonstrating the potential of this architecture to address the long wavelength operation of silica based fibre lasers with high efficiency.
We have demonstrated the highest reported output power from a mid-IR ZGP OPO. The laser is a cascaded hybrid system consisting of a thulium fibre laser, Ho:YAG solid state laser and a Zinc Germanium Phosphide parametric oscillator. The system produces 27 W of output power in the 3-5 μm wavelength range with an M(2) = 4.0 when operating in a repetitively q-switched mode, and a modulated peak output power of 99 W at a reduced duty cycle of 25%.
We present a novel large-mode-area thulium-doped fibre with a large pedestal design. We discuss the advantages of this large pedestal fibre in the context of overcoming limitations imposed by cleaving and splicing tolerances. Finally we demonstrate the use of such a fibre in constructing monolithic fibre lasers operating at 1.95 µm with 170 W of output power, 0.1 nm line-width and a diffraction limited beam quality of M(2)(X,Y) = 1.02, 1.03.
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