High-repetition-rate, sub-nanosecond and narrow-bandwidth fiber-laser-pumped green laser for photon-counting shallow-water bathymetric Lidar

We have demonstrated, to the best of our knowledge, the first photon-counting shallow-water bathymetric Lidar based on a fiber-laser-pumped green laser. An Ytterbium-doped, fiber master oscillator power amplifier is developed as the fundamental laser, delivering 2.3 W pulses with widths of 450 ps at 500 kHz and bandwidths of 0.04 nm centered at 1064.1 nm. Its wavelength is frequency doubled to 532 nm, located within the transparent window of water, with an average power of 0.95 W. A coaxial transmitting and receiving photon-counting shallow-water bathymetric Lidar is constructed based on the fiber-laser-pumped green laser. Subsequent day-time shipborne experiments in Thousand-Island Lake show that the largest slope distance of similar to 3.1 m, more than twice as much as the Secchi depth (similar to 1.5 m), can be achieved indicating its capability of practical shallow-water bathymetry.