Acousto-optic interactions and devices in a spherical waveguide

A spherical surface was previously shown experimentally to be capable of simultaneously guiding, collimating and focusing a light beam, and thus serving as an alternative substrate for realization of acousto-optic (AO) Bragg cell modulators and related device modules. In this paper we report, for the first time, a theoretical treatment for such spherical guided-wave AO interactions together with new experimental results at significantly higher surface acoustic wave centre frequency (500 MHz) using a LiNbO 3 hemisphere block. The theoretical analysis for the optical and the acoustic waves is carried out using the lowest-order asymptotic expansions and the resulting AO Bragg diffraction calculated using the Green function technique.