Взаємодія світла з поздовжніми акустичними хвилями, збудженими п’єзоперетворювачами скінченних розмірів в ізотропному середовищі

Abstract

У роботі із використанням інтеграла Релея–Зомерфельда розраховано деформації в акустичному пучку, збудженому прямокутним п’єзоперетворювачем. На основі одержаних результатів визначено величини дифракційної ефективності взаємодії плоскої оптичної хвилі і акустичного пучка, збудженого прямокутним п’єзоперетворювачем.The deformation in acoustic beam excited by the rectangle piezo-transducer is calculated by Rayleigh-Sommerfeld integral consideration. This calculation is carried out for the longitudional acoustic waves propagating in the isotropic medium. The analytical consideration of the deformations is undertaken for the ’shadow’ and the Fraunhofer (the far area) regions determined throw the Fresnel parameter of the acoustic field. The deformations in the Fresnel region (the nearest area) are expressed by the Fresnel integrals which can be calculated only numerically. Based on the obtained expressions, the changes of the dielectric permittivity is calculated for the acoustic beam in the ’shadow’ and the Fraunhofer regions. In turn, these results are used for the determination of the diffraction efficiency of the acousto-optic interaction of the plane optical wave with acoustic beam excited by the rectangle piezo-transducer in the mentioned regions. As it is shown, the obtained expressions for the diffraction efficiency in the ’shadow’ and the Fraunhofer regions are essentially different. At that the expression for the diffraction efficiency in ’shadow’ region coincides with the one for the diffraction efficiency in the case of interaction between plane optical and plane acoustical waves. As it is followed from our consideration, the regions of the ’shadow’ (or the nearest area) are predominantly realized for the longitudional acoustic waves propagating in isotropic media.