To achieve stable output from a folded-acceleration-cavity rotating-mirror Q-switched laser and effectively reduce thermal damage; to address issues in traditional rotating-mirror Q-switching technology—such as mechanical vibration and degraded laser performance resulting from increased mirror rotation speeds; to explore methods for overcoming speed limitations and significantly improving Q-switched pulse performance; and to provide a feasible solution for achieving high-peak-power, narrow-pulse-width laser output.

An anti-vibration and positioning device was constructed, and a dual-slit rotating-mirror phase-synchronization signal detection device and high-precision timing control system were designed and developed. This system enabled precise synchronization of the motor phase with the pumping timing, achieving precise matching between the cavity-forming moment of the rotating mirror and the moment when the population inversion in the gain medium reached saturation. Through theoretical analysis, a dynamic model of cavity loss was established and experimentally validated in a folded acceleration cavity of an Er,Cr:YSGG laser. The pump energy, repetition rate, and rotating-mirror speed were controlled, and the laser output energy, pulse width, and stability were measured.

The developed folded acceleration cavity doubled the equivalent rotation speed of the rotating mirror without increasing mechanical load. The synchronous detection and timing control system resolved the challenge of precisely synchronizing the motor phase with the pumping timing, significantly enhancing laser pulse-width compression and peak-power output capabilities while improving pulse energy stability. The folded-acceleration-cavity Er,Cr:YSGG rotating-mirror Q-switched laser, operating at a repetition rate of 10 Hz and a mirror rotation speed of 600 r/s, achieved a single-pulse energy of 41.5 mJ and a pulse width of 68.4 ns(Fig.6), corresponding to a peak power of 606.7 kW, with a standard deviation of output energy fluctuations of less than 3.62%(Fig.7). This result indicated that the combination of a folded acceleration cavity and a high-precision timing control system significantly enhanced laser pulse-width compression and peak-power output capabilities without increasing the physical rotation speed of the rotating mirror, while maintaining highly stable output and enabling long-term stable operation.

By combining a folded acceleration cavity with high-precision timing control, this approach effectively increases the equivalent rotation speed of the rotating mirror, overcoming the mechanical limitations of traditional rotating-mirror Q-switched lasers and achieving highly stable, high-energy, narrow-pulse-width 3 μm laser output. This provides a verifiable technical solution and experimental basis for the application of rotating-mirror Q-switching technology in high-energy, narrow-pulse-width, and engineered miniaturized laser systems.