Acousto-Optics and Applications New Acousto-Optic Regime of Interaction in Media Possessing Strong Elastic Anisotropy

We present results on theoretical and first experimental investigation of a new regime of acousto-optic in-teraction existing in acoustically anisotropic medium. We defined the new regime as semi-collinear or mixed interaction since it combined properties of the traditional non-collinear diffraction and the pure collinear interac-tion. The peculiar phenomenon was registered in the tellurium dioxide crystal due to the extremely strong elastic anisotropy of the material. Application of a specific cut of the crystal provided observation of the effect in the middle infrared at the optical wavelength 3.39 µm and at the acoustic frequencies limited to 300 MHz. The ob-served interaction was characterized by a non-collinear propagation of incident light with respect to acoustic energy flow and simultaneously a collinear propagation of diffracted radiation along the acoustic energy flow. A brief the-oretical analysis of the interaction based on wave vector diagrams and two-dimensional coupled wave equations is included in the presentation. Finally, we describe in the paper, the setup and basic details of the carried out acousto-optic experiment