Bathymetry of a macro-pulsed chaotic laser based on a 520 nm laser diode subject to free space optical feedback.

We generate a macro-pulsed chaotic laser based on pulse-modulated laser diode subject to free space optical feedback, and demonstrate the performance of suppressing backscattering interference and jamming in turbid water. The macro-pulsed chaotic laser with a wavelength of 520 nm as a transmitter is used with a correlation-based lidar receiver to perform an underwater ranging. At the same power consumption, macro-pulsed lasers have higher peak power than in the continuous-wave form, enabling the former to detect longer ranging. The experimental results show that a chaotic macro-pulsed laser has excellent performance of suppressing the backscattering of water column and anti-noise interference compared with traditional pulse laser, especially by multiple accumulations about 10∼30 times, and target position can still be determined when SNR is -20 dB.