Solid-state YVO_4/Nd:YVO_4/KTP green laser system for the generation of subnanosecond pulses with adjustable kilohertz repetition rate

摘要

A solid-state green laser generating subnanosecond pulses with adjustable kilohertz repetition rate is presented. This pulse laser system is composed of a Q-switched and mode-locked YVO_4/Nd:YVO_4/KTP laser simultaneously modulated by an electro-optic (EO) modulator and a central semiconductor saturable absorption mirror. Because the repetition rate of the Q-switched envelope in this laser depends on the modulation frequency of the EO modulator, so long as the pulsewidth of the Q-switched envelope is shorter than the cavity roundtrip transmit time, i.e., the time interval of two neighboring mode-locking pulses, only one mode-locking pulse exists underneath a Q-switched envelope, resulting in the generation of subnanosecond pulses with kilohertz repetition rate. The experimental results show that the pulse-width of subnanosecond pulses decreases with increasing pump power and the shortest pulse generated at 1 kHz was 450 ps with pulse energy as high as 252 μJ, corresponding to a peak power of 560 kW. In addition, this laser was confirmed to have high stability, and the pulse repetition rate could be freely adjusted from 1 to 4 kHz.