High-power and high-beam-quality acousto-optic Q-switched hybrid-cavity slab laser

We propose a high-power, high-beam-quality hybrid-cavity acousto-optic (AO) Q-switched slab laser. This laser employs a large-area-pumped Nd:YAG slab laser crystal and is based on a hybrid resonator cavity combining stable and off-axis unstable modes, incorporating large-aperture acousto-optic Q-switching technology to achieve direct output of high-power nanosecond lasers. By establishing a rate equation for acousto-optic Q-switching in the Nd:YAG slab laser oscillator, we simulate and optimize the laser performance, effectively enhancing the laser conversion efficiency. Furthermore, we design a hybrid cooling temperature control structure for the slab crystal, effectively suppressing the thermal lensing effect along the thickness direction of the crystal. The experimental results demonstrate that the output power of the laser reaches 3062 W at a pump power of 9800 W, with an optical-to-optical conversion efficiency of 31%, a pulse width of 46 ns, a single-pulse energy of 153.1 mJ, and beam quality factors of Mx2≤4.8 and My2≤3.5. The hybrid-cavity acousto-optic Q-switching design simplifies the optical path structure, reduces the number of components in the cavity, and effectively minimizes the laser volume. Additionally, this laser shows broad application potential in the field of laser cleaning, achieving a cleaning grade of Sa 2.5 and an efficiency of 25m²/h when used for line-laser rust removal on Q235 carbon steel with an initial rust grade of C.