基于新型几何结构的二维声光Q开关设计与性能研究

doi:10.16553/j.cnki.issn1000-985x.2025.0248

摘要/Abstract

摘要： 二维声光Q开关是激光调Q系统的核心器件，其性能直接影响激光脉冲的质量。本文提出一种基于新型几何结构的二维声光Q开关设计，旨在解决传统直角三棱柱结构器件中回返声波干扰、衍射光斑畸变、调制波形出现台阶状畸变及水冷结构复杂等问题。该设计通过重构熔融石英材质的声光晶体几何形状，使声波在晶体中形成特定的反射路径，确保声波在首次正交后，其反射路径在空间上自动错开，从而规避回返声波对实际主工作区的干扰问题。同时，新设计将传统三面水冷结构简化为两个主要水冷块，在轻微提高晶体加工精度要求的前提下，大幅降低了封装组装难度与整体成本。结果表明，当工作光波长为1 064 nm、有效通光孔径为3 mm×3 mm （矩形）、双路射频驱动功率均为47 W的条件下，该器件的二维衍射效率达98.5%，衍射光斑呈规则网格分布，调制波形纯净无台阶状畸变。热稳定性测试证实，尽管工作温度较传统结构有所升高，但其衍射效率与波形在长期工作中保持稳定。本工作为解决声光器件中的回返声波干扰问题提供了一条具有普适性的设计路径，在保证高性能的同时，实现了器件的紧凑化与工艺的简化。

关键词: 二维声光Q开关; 几何结构; 声光晶体; 换能器; 熔融石英; 衍射效率; 波形; 回返声波

Abstract: 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.

Key words: two-dimensional acousto-optic Q-switch; geometric structure; acousto-optic crystal; transducer; fused silica; diffraction efficiency; waveform; return acoustic wave

中图分类号:

O734

许智宏, 张雪封, 王城强, 王帅华, 吴少凡. 基于新型几何结构的二维声光Q开关设计与性能研究[J]. 人工晶体学报, 2026, 55(4): 584-593.

XU Zhihong, ZHANG Xuefeng, WANG Chengqiang, WANG Shuaihua, WU Shaofan. Design and Performance Study of Two-Dimensional Acousto-Optic Q-Switch with New Geometric Structure[J]. Journal of Synthetic Crystals, 2026, 55(4): 584-593.

图/表 12

图1 传统二维声光Q开关的结构图（a）及其衍射光斑示意图（b）

Fig.1 Structural diagram of traditional two-dimensional acousto-optic Q-switch （a） and schematic diagram of its diffraction spot （b）

图2 传统二维声光Q开关的声波路径。（a）理想情况；（b）因加工偏差导致的失效情况；（c）因声场旁瓣引起的失效情况

Fig.2 Acoustic paths of traditional two-dimensional acousto-optic Q-switch. （a） Ideal situation；（b） failure caused by processing deviation；（c） failure caused by acoustic field side lobes

图3 传统二维声光Q开关的实际异常现象。（a）换能器1单独工作时的衍射光斑；（b）换能器2单独工作时的衍射光斑；（c）共同工作时的台阶状波形

Fig.3 Actual anomalous phenomena of traditional two-dimensional acousto-optic Q-switch. （a） Diffraction spot when transducer 1 operates independently；（b） diffraction spot when transducer 2 operates independently；（c） stepped waveforms when working simultaneously

图4 新型几何结构二维声光Q开关的声波路径设计。（a）声波传播的反射主路径；（b）考虑声发散特性的路径

Fig.4 Acoustic path design of two-dimensional acousto-optic Q-switch with new geometric structure. （a） Main reflected path of acoustic wave propagation；（b） path considering acoustic divergence characteristics

图5 二维声光Q开关的机械结构对比图。（a）传统结构；（b）新设计

Fig.5 Comparison diagram of mechanical structure of two-dimensional acousto-optic Q-switches. （a） Traditional structure；（b） new design

图6 二维声光Q开关的热仿真对比图。（a）传统结构；（b）新设计

Fig.6 Thermal simulation comparison diagram of two-dimensional acousto-optic Q-switches. （a） Traditional structure；（b） new design

图7 新型几何结构二维声光Q开关的实物照片。（a）声光晶体；（b）器件

Fig.7 Physical photos of two-dimensional acousto-optic Q-switch with new geometric structure. （a） Acousto-optic crystal；（b） device

图8 新型几何结构二维声光Q开关的衍射效率曲线和衍射光斑分布

Fig.8 Diffraction efficiency curve and diffraction spot distribution of two-dimensional acousto-optic Q-switch with new geometric structure

图9 新型几何结构二维声光Q开关的调制波形图

Fig.9 Modulation waveforms of a two-dimensional acousto-optic Q-switch with new geometric structure

图10 新型几何结构二维声光Q开关的阻抗曲线

Fig.10 Impedance curve of two-dimensional acousto-optic Q-switch with new geometric structure

图11 二维声光Q开关的温度热成像对比图。（a）传统结构；（b）新设计

Fig.11 Temperature thermal imaging comparison diagram of two-dimensional acousto-optic Q-switches. （a） Traditional structure；（b） new design

图12 新型几何结构二维声光Q开关的长期稳定性测试结果。（a）晶体温度和调制波形；（b）衍射效率

Fig.12 Long-term stability test results of two-dimensional acousto-optic Q-switch with new geometric structure. （a） Crystal temperature and modulation waveform；（b） diffraction efficiency

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