| Optical wave depolarization resulting from an interaction with a surface acoustic wave has been analyzed for conditions where the acoustic beam does not lie in the optical plane of incidence. The depolarization resulting from the acousto-optic interaction is predicted from the scattered optical field as a function of the optical incident angle, {dollar}Theta{dollar}, and the acoustic incident angle, {dollar}varphi{dollar}. The acoustic contributions to the scattered optical field considered in the analysis include the corrugation of the surface and the elasto-optic effect near the surface. In the physical case modeled, the acoustic wave propagates in fused silica and the optical wave propagates in air. The contributions from acoustic-to-optical wave number ratio, K/k, and acoustically-driven corrugation and elasto-optic surface amplitude effects are investigated with regard to incident-to-scattered polarization states: S to S, S to P, P to S, and P to P. A general scattering cross-section model is used to predict depolarization over {dollar}-90 < Theta < +90{dollar} degrees. Scattering cross-sections for {dollar}0 < rm{lcub}K/k{rcub} leq 0.1{dollar} are modeled by computer analysis for coplanar ({dollar}varphi{dollar} = 0) and non-coplanar cases ({dollar}0 < varphi < 90{dollar}). The presence of incident-to-scattered depolarization, initially identified as a complementary change in the non-coplanar cross-section values for scattered S and P states, is also investigated by the Jones method of optical matrices. Using Jones notation to describe the initial-to-scattered polarization states, an optical analog method model was developed with transfer matrix coefficients defined by the scattered light field from the general scattering cross-section model. From this, the scattered optical field amplitudes were shown to exhibit changes in polarization amplitudes that directly correlate to the changes in general scattering cross-section model. The optical analog model was then modified, using the coefficients of the Jones matrix, to generate a Stokes transfer matrix describing the interaction. Re-defining the incident S- and P-states in Stokes notation, the change in scattered optical intensity was tested for similar cases of depolarization studied by the Jones method. The results were finally compared to the scattering cross-section model and Jones model and were found to be in direct correlation with the predictions for depolarization. This new approach has been shown to predict depolarization by optical methods. |
