Eye-safe fiber laser for long range 3D imaging applications

We report an all-fiber Er/Yb master oscillator power amplifier at 1.55 μm, delivering 135 μJ pulses with 6 ns duration (full width at half-maximum) at 100 kHz pulse repetition frequency, limited by stimulated Brillouin scattering. The output contains <1% amplified spontaneous emission and has a beam quality of 𝑀�2=1.1. By seeding with a high-power distributed-feedback laser diode, only two fiber amplification stages are needed, which represents a low overall system complexity compared to reported sources of similar performance. With an optical-to-optical efficiency of 29% and a robust alignment-free design, the source is well suited for field applications in 3D imaging with a several-kilometer range, and we present results from using it in an in-house-developed scanning lidar system.