Simultaneous acousto-optic diffractions by two lobes of a shaped phased-array transducer

Abstract

We consider simultaneous diffractions of light by two lobes of sound radiation pattern in an acousto-optic modulator which is built on SiO 2 single crystal and has two-element phased-array transducer with the fixed phase shift  .Implementation of this diffraction type greatly improves power efficiency of the device. Transducer shaping is used to steer the lobes and satisfy the Bragg's conditions for simultaneous acousto-optic diffractions. The conditions of the diffraction are defined and a mathematical model for calculating diffraction efficiency is suggested. It is shown that a parallel diffraction regime is almost three times more energy-efficient than a serial regime. Several configurations of transducer elements' shape are analyzed. In particular, changes in the dimensions of diamond-shaped elements are shown to allow adjusting the operating frequency within 23%. An experimental sample of the device is built.