Linearly polarized and narrow-linewidth pulse generation at high repetition rate from an all-fiber gain-switched Thulium-doped fiber laser

• A gain-switched Thulium-doped fiber laser with an all-fiber configuration is presented.
• Stable 2 μm pulses output has been achieved at high repetition rate up to 500 kHz.
• The slope efficiency of the laser system is as high as 55.1%, with a high optical-to-optical conversion efficiency of 47.7%.
• The fiber laser output is more than 98% linearly polarized.
• The spectral linewidth of the laser system is as narrow as 0.0476 nm, restricted by the resolution limit of the optical spectrum analyzer.

Narrow-linewidth and linearly polarized operation at high repetition rate of an all-fiber gain-switched Thulium-doped fiber laser is presented. The laser produces stable 135 ns pulses with maximum average output power of 960 mW at repetition rate of 500 kHz, corresponding to maximum pulse energy of 1.92 μJ and a slope efficiency of 55.1% with respect to 1.55 μm pump power. The center wavelength of 1926.7 nm with a spectral bandwidth of <50 pm is achieved.