为了提高声光移频器的性能,对其内部声光晶体(AOC)和压电超声换能器(PZT)电极之间的位置失配特性进行研究,并深入分析AOC和PZT电极之间几类不同的几何装配错位关系。通过构造AOC与电极失配的三维有限元模型,在不同轴向装配错位的条件下对AOC中的超声波声场进行仿真分析。根据超声波的声场分布特性,可以发现几何装配错位会导致AOC内部形成不发生声光相互作用的区域,并揭示此区域长度与错位量的关系。通过分析声光相互作用区与不发生声光相互作用区之间的光学界面,发现位置失配会在输出光中发生双光束干涉效应,其对实际光学系统的输出会产生影响。基于双光束干涉原理搭建一种测量不发生声光相互作用区域长度的实验系统,所得结果证明理论分析的合理性。

In order to improve the performance of the acousto-optic frequency shifter, the positional mismatch characteristics between the internal acousto-optic crystal (AOC) and piezoelectric ultrasonic transducer (PZT) electrodes are studied, and several geometric assembly mismatches between AOC and PZT electrodes are analyzed. By constructing a three-dimensional finite element model of AOC and electrode mismatch, the ultrasonic sound field in the AOC is simulated and analyzed under different axial assembly dislocation conditions. According to the acoustic field distribution characteristics of ultrasound, it can be found that the geometrical assembly dislocation will lead to the formation of an area without acousto-optic interaction inside the AOC, and the relationship between the length of this area and the amount of dislocation can be revealed. By analyzing the optical interface between the acousto-optic interaction area and the non-acousto-optic interaction area, it is found that the position mismatch will cause the double-beam interference effect in the output light, which will affect the output of the actual optical system. Based on the principle of double-beam interference, an experimental system is built to measure the length of without acoustic interaction occurs region, and the results prove the rationality of the theoretical analysis.