A 1.6-μm pumped 1.9-μm thulium-doped fluoride fiber laser and amplifier of very high efficiency

Results are presented for color center, and semiconductor, laser pumping of the 1.82 mu m transition in a thulium-doped fluoride fiber. As an amplifier small signal gain efficiencies of 8.1 dB/mW were attained with a maximum gain of 36.5 dB being achieved for around 17-18 mW of launched pump power. As a laser a maximum slope efficiency of 84% and a minimum threshold for oscillation of 340 mu W was also demonstrated for this system. Furthermore by suppressing all reflections down to < 36 dB superfluorescent or ASE output was observed. In achieving efficient operation with a diode laser pump source this system shows strong commercial potential.