High average power single-frequency nanosecond laser tunable from 766 nm to 775 nm and 1535 nm to 1570 nm based on a...

A high-average-power narrow linewidth coherent nanosecond (ns) pulsed laser operating in a broad wavelength range is a crucial source for optical sensors, spectroscopy, lidar, generation of deep-ultraviolet lasers, and many more applications. Here, we propose an innovative technical approach for the generation of high-average-power single-frequency ns laser tunable from 766 nm to 775 nm and 1535 to 1570 nm based on a coherent optical parametric generator (OPG), utilizing a single-frequency ns green laser as the pump source in conjunction with a continuous-wave tunable 1.5 µm single-frequency laser as the seeding source. The OPG is based on a non-critical phase-matching LBO crystal, pumped by an 84 W 515 nm 6.10 ns 100 kHz pulsed single-frequency laser, second harmonic of a home-made 135 W fiber-solid hybrid master-oscillator power amplification system, and seeded by a 1.5 µm single-frequency fiber laser tunable from 1535-1570 nm. Consequently, the OPG achieves high-power single-frequency ns pulse output tunable from 766 nm to 775 nm and 1535 nm to 1570 nm, as signal and idler, respectively. At 775 nm, the signal laser obtains an average power of 33.76 W, corresponding to a conversion efficiency of 40.19% with a pulse width of 5.16 ns and a peak power of 65.42 kW, while maintaining excellent beam quality (Mx2=1.26, My2=1.23). In addition, the idler laser reaches a maximum average power of 16.00 W with a pulse width of 5.00 ns and a peak power of 32.00 kW at 1535 nm. To the best of our knowledge, this research realizes the highest average power of dual-band tunable single-frequency ns pulse laser output based on a seeded LBO-OPG.