基于新型几何结构的二维声光Q开关设计与性能研究OA

The two-dimensional acousto-optic Q-switch is a key component in laser Q-switching systems.Traditional devices based on a right-angle triangular prism geometry suffer from inherent drawbacks,including return acoustic wave interference,diffraction spot distortion,stepped distortion in the modulation waveform,and a complex three-sided water-cooling structure.This work proposes a new geometric structure for a two-dimensional acousto-optic Q-switch to fundamentally eliminate return acoustic wave interference,simplify thermal management,and achieve high diffraction efficiency with clean modulation waveforms,while maintaining compactness and reliability for high-power laser applications. In this paper,a fused silica acousto-optic crystal with a non-symmetrical wedge geometry was designed.Unlike the conventional right-angle prism,the new geometry structure ensured that after the first orthogonal acousto-optic interaction of the acoustic wave,the reflected acoustic paths were spatially offset from the main working region,thereby avoiding return wave interference.Two orthogonal y-36°LiNbO3 transducers were bonded onto the crystal,with a center frequency of 27.12 MHz and an operating wavelength of 1 064 nm.The effective aperture is 3 mm×3 mm(rectangular)and the acousto-optic interaction length was 42 mm.The water-cooling structure was simplified from three-sided water-cooling structure to two main water-cooling blocks,reducing assembly complexity. Experimental results show that with dual-channel radio frequency(RF)drive power of 47 W per channel,the two-dimensional diffraction efficiency reaches 98.5％,and the diffraction spot pattern exhibits a regular grid distribution without distortion.The modulation waveform shows a steep rising edge(～307.7 ns)and falling edge(～774.8 ns)with a flat top,free from the stepped distortion observed in conventional devices.The impedance curve at 27.12 MHz is smooth and close to 50.2 Ω,matching standard RF systems.Thermal imaging reveals a steady-state crystal temperature of approximately 69.7℃under dual-channel RF drive power of 47 W per channel(compared to 54.4℃ for the conventional design),which is well below the softening point of fused silica.A 4 h continuous aging test confirms excellent thermal stability.The temperature stabilizes at(71±1)℃,the diffraction efficiency remains between 97.5％and 98.7％(standard deviation～0.28),and the modulation waveform shows no degradation. In this paper,the proposed two-dimensional acousto-optic Q-switch with new geometric structure successfully eliminates return acoustic wave interference through spatial path control,providing a universal design approach applicable to other acousto-optic materials(e.g.,TeO2,SiO2,Ge)for different laser wavelengths.Although the new geometry structure imposes slightly higher precision requirements on crystal fabrication,the simplified two water-cooling block structure reduces overall assembly cost and complexity,while maintaining high performance and long-term reliability.This work offers a practical and innovative pathway for developing advanced acousto-optic devices.