High-power single-frequency narrow-linewidth nanosecond pulsed fiber laser based on triangle-shaped pulse

A narrow-linewidth single-frequency Yb-doped nanosecond pulsed fiber laser with 27-kW peak power was demonstrated in this work. By employing the novel triangle-shape pulse with a 1-ns rise time and 13-ns fall time, the spectral linewidth of 88 MHz was achieved at the maximum output power. The signal to noise ratio was about 33 dB and no obvious residual pump power within the output laser. To the best of our knowledge, it is the first time that the performance of triangle-pulse fiber amplifier was demonstrated.