We present a tunable, high power cladding-pumped holmium doped fiber laser. The laser generated >15 W CW average power across a wavelength range of 2.043 - 2.171 μm, with a maximum output power of 29.7 W at 2.120 μm. The laser also produced 18.2 W when operating at 2.171 µm. To the best of our knowledge this is the highest power operation of a holmium doped laser at a wavelength >2.15 µm. We discuss the significance of background losses and fiber design for achieving efficient operation in holmium doped fibers.

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We present a monolithic, robustly polarised thulium fibre laser which produces pulses with 25 ns duration and energy of up to 35 µJ. A pulsed 1.55 μm source was used to gain switch the laser at repetition rates of up to 300 kHz, producing average powers of up to 8 W at 2.044 µm. To the best of our knowledge this is the highest power gain-switched thulium fibre laser and it is also the first with a linearly polarised output. The large repetition rate, pulse energy and average power will enable efficient energy extraction from a large mode-area, polarisation maintaining thulium fibre amplifier.

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.