Yushkov Konstantin B
Appl Opt. 2021 Aug 20;60(24):7113-7121. doi: 10.1364/AO.427199.
Anisotropic acousto-optic diffraction in crystals is the fundamental phenomenon that is used to design acousto-optic tunable filters. Noncritical and quasicollinear phase-matching geometries of Bragg acousto-optic diffraction are compared for acoustic symmetry planes in four crystal systems (tetragonal, trigonal, orthorhombic, and monoclinic). The results for uniaxial crystals are reviewed and generalized for biaxial crystals. It is shown that cubic frequency dependence on the Bragg angle exists in two symmetry planes of orthorhombic crystals and conditionally exists in the symmetry plane of monoclinic crystals. It is also shown that there are two points in the symmetry plane of monoclinic crystals where noncritical phase matching takes place in quasicollinear diffraction geometry that can be used to design high-resolution tunable filters. Phase-matching configurations in -iodic acid and potassium gadolinium tungstate crystals are analyzed.
晶体中的各向异性声光衍射是用于设计声光可调滤波器的基本现象。针对四种晶体系统（四方晶系、三角晶系、正交晶系和单斜晶系）中的声学对称平面，比较了布拉格声光衍射的非临界和准共线相位匹配几何结构。对单轴晶体的结果进行了综述，并推广到双轴晶体。结果表明，在正交晶系的两个对称平面中存在立方频率对布拉格角的依赖性，在单斜晶系的对称平面中则有条件地存在这种依赖性。还表明，在单斜晶系的对称平面中有两个点，在准共线衍射几何结构中会发生非临界相位匹配，可用于设计高分辨率可调滤波器。分析了碘酸和钨酸钆钾晶体中的相位匹配配置。
