Flexible high-power laser system with adjustable pulse duration from 100 ps to 10 ns

A tailorable high-power laser with widely continuous tunable pulse width operating at 1064, 532, and 355 nm is developed based on a fiber and solid-state hybrid master oscillator power amplifier (MOPA) system. A gain controllable high-repetition-rate solid-state pre-amplifier is designed to sufficiently suppress the leading-edge spike of the amplified laser pulse originating from the gain-switched semiconductor seed laser. The MOPA system achieves a maximum average output power of 230 W at 1 MHz and a single-pulse energy up to 1.5 mJ at 100 kHz operating at 1064 nm with a full width at half-maximum (FWHM) in the spectrum of 0.1 nm and an adjustable pulse width from 100 ps to 10 ns. By using LBO crystals for second-harmonic generation (SHG) and subsequent third-harmonic generation (THG), a maximum 532 nm green and 355 nm ultraviolet (UV) output power of 116 W and 70 W, respectively, is obtained with the repetition rate of 1 MHz and pulse width of 100 ps. The corresponding output laser beam quality factors of a 355 nm UV laser are measured to be M x 2 =1.18 and M y 2 =1.23, and the output power stability is RMS =1.23 % under 12 h operation. Our results provide a new method for high-power wide pulse width tunable sub-nanosecond to nanosecond laser generation, and they demonstrate significant potential for applications in photoconductive switch excitation, precision micromachining, and laser cutting.