Balakshy Vladimir I, Voloshin Andrey S, Molchanov Vladimir Ya
Lomonosov Moscow State University, Department of Physics, Leninskiye Gory 1, 119991 Moscow, Russia.
Lomonosov Moscow State University, Department of Physics, Leninskiye Gory 1, 119991 Moscow, Russia.
Ultrasonics. 2015 May;59:102-8. doi: 10.1016/j.ultras.2015.02.002. Epub 2015 Feb 11.
Influence of acoustic beam energy walk-off on characteristics of Bragg diffraction of light is studied theoretically and experimentally by the example of a paratellurite single crystal. Two cases of isotropic and anisotropic light scattering are examined. Angular and frequency characteristics of acousto-optic interaction are calculated in wide ranges of Bragg angles and ultrasound frequencies by means of modified Raman-Nath equations. It is shown that the walk-off can substantially change the width of angular and frequency ranges, resulting in their narrowing or broadening subject to position of the operating point in the Bragg angle frequency characteristic. Coefficients of broadening are introduced for characterization of this effect. It is established that frequency dependences of the broadening coefficients are similar to the Bragg angle frequency characteristics. Experimental verification of the calculations is carried out with a paratellurite cell of 10.5° crystal cut.
以偏亚碲酸盐单晶为例，从理论和实验两方面研究了声束能量离散对光的布拉格衍射特性的影响。研究了各向同性和各向异性光散射的两种情况。通过修正的拉曼 - 纳特方程，在较宽的布拉格角和超声频率范围内计算了声光相互作用的角度和频率特性。结果表明，离散会显著改变角度和频率范围的宽度，根据布拉格角频率特性中工作点的位置，导致其变窄或变宽。引入展宽系数来表征这种效应。确定展宽系数的频率依赖性与布拉格角频率特性相似。使用切割角度为10.5°的偏亚碲酸盐池对计算结果进行了实验验证。
