Half-mJ All-Fiber-Based Single-Frequency Nanosecond Pulsed Fiber Laser at 2-

摘要

We report a high energy, high peak power, all-fiber-based single-frequency ${sim}{rm 15}hbox{-}{rm ns}$ pulsed laser source at ${sim}{rm 1918.4}~{rm nm}$ in master oscillator-power amplifier configuration. The pulsed fiber laser seed was achieved by directly modulating a continuous-wave single-frequency fiber laser using an electro-optic modulator driven by an arbitrary waveform generator to pre-shape the pulses before amplification to mitigate pulse steepening and dynamic gain saturation. One piece of large $(25hbox{-}mu{rm m})$ core, polarization-maintaining highly thulium-doped germanate glass fiber was used in the power amplifier stage to boost the energy and the peak power of the 15-ns pulses to ${>}{rm 0.5}~{rm mJ}$ and ${>}{rm 33}~{rm kW}$ without any nonlinearities.