A plane wave derivation of the Bragg acoustooptic equations and their application to the scattering of finite-width optical beams

摘要

The equations describing the interaction between an optical beam and an acoustic wave are derived using plane waves derived from elementary scattering sources. The results obtained are in good agreement with other well-known methods such as the differential difference equation approach. The equations are applied to the acousto-optic interaction in the weak and strong approximations and also to the scattering of finite-width optical beams with rectangular and Gaussian profiles. It is shown that in both cases the second or backscattered beam (A′0) produces a substantial modification in the through beam (A0) resulting in an intensity null at some point in the beam profile. Equations are derived for the diffraction efficiency in finite-width beams and it is shown that in order to achieve maximum efficiencies it is essential to use small values of the parameter γ =Lθ