Review of recent progress on single-frequency fiber lasers
We demonstrate a high power all-fiber single frequency Tm-doped fiber amplifier. The maximum output power reached 102 W and the central wavelength was 1.97 μm. The single frequency laser signal from a seed laser was amplified based on a monolithic master oscillator power amplifier (MOPA) configuration. The slope efficiency was about 50% against the absorbed pump power. Neither parasitic lasing nor nonlinear effect was observed in the monolithic fiber amplifier. The SBS threshold of the single frequency Tm-doped fiber amplifier was analyzed and estimated. The output power is not limited by the SBS threshold and could be further improved by increasing the pump power. To the best of our knowledge, this is the first demonstration of average power exceeding 100 W from monolithic all-fiber laser near 2 μm wavelength.