Self- Q -switch regime based on a beat effect with a dual-frequency microchip laser

A self-Q-switch regime based on the dual-frequency beat effect with a microchip crystal cavity is demonstrated. Unlike the microchip based passively Q-switched laser, the pulses are generated without a saturable absorber. It is the microchip's dual-crystal structure along with the beat effect that leads to the Q value's modulation and offers the possibility for generating Q-switched pulses. A Nd:YAG microchip and a LiTaO3 microchip compose the laser cavity by the optical cement method. The stress and thermal induced anisotropy of the Nd:YAG crystal offers the dual-frequency component and the LiTaO3 microchip offers polarization selection for the beat effect. The dual-frequency component experiences periodically changed loss with the variation of the two frequencies' phase difference, due to the polarization selection by the LiTaO3 chip. The principle of the beat effect based self-Q-switch regime is analyzed and Q-switched pulses with a repetition rate of around 1 MHz are achieved experimentally. This phenomenon gives us a way to obtain pulsed lasers and might be interesting to those conducting research on Q-switch lasers and light-borne microwave generation.