Highly efficient, kW peak power, 1.55 µm all-fiber MOPA system with a diffraction-limited laser output beam

We report a high-efficiency, single-mode, all-fiber pulsed laser system built in a master oscillator power amplifier format, operating in the eye-safe (λ ~1,549 nm) spectral range, providing over 1.5 W of average output power with up to 51 dB of total signal gain. It comprises the flexibility of smooth pulse duration control from single ns to 260 ns with independently tunable repetition rate ranging from 40 kHz to 1 MHz. Pulses as short as 4 ns with up to 20 μJ energy and corresponding peak power of 5 kW are demonstrated. The laser system delivered a nearly diffraction-limited beam with M 2 ~1.