High-Energy Near Transform-Limited Pulses From an Ultrafast Thulium-Doped All-Fiber MOPA

We report on a high-energy ultrafast thulium-doped all-fiber master oscillator power amplifier system with a pulse energy of 85 nJ and a pulsewidth of 8 ps. The seed laser was passively mode-locked by a semiconductor-saturable absorber mirror to generate average power 16 mW at a pulse repetition rate of 14.7 MHz in a linear cavity. A one-stage single-mode thulium-doped fiber amplifier was used directly to boost average power to 1.25 W. The laser center wavelength and the spectral bandwidth were 1963.5 and 0.7 nm, respectively, and the time-bandwidth product of the laser pulse was 0.44.