An All Fiber 1.94 µm Nanosecond Pulse Laser Amplified by Highly Tm³⁺-Doped Silicon Fibers

We present an all-fiber 1.94 μm nanosecond pulse laser in master oscillation-power amplifier configuration. A dual-FBGs gain-switched Tm³⁺-doped fiber laser is built and is used as the seed laser. The output characteristics of the amplifier are studied at different pulse repetition rates, and the maximum output energy of 500 μJ is achieved under incident pump power of 39 W. The emitting spectra are checked at 5 and 10 kHz, and no obvious nonlinear effects are observed in the spectrum of the amplified laser. The beam quality factor is M²=2.1±0.03 measured by the traveling knife-edge method, and the laser beam spot is also monitored by an infrared vidicon camera.