Improvement of diffraction efficiency in surface-acoustic-optic devices by means of multilayered structure

Abstract

A strain-controlling film to change acoustic strain distributions in the interaction region between acoustic surface waves and optical guided waves is introduced to improve the Bragg-diffraction efficiency in surface-acoustic-optic devices. An improvement of about 2 orders of magnitude has been achieved in the efficiency of TM0-TM0 diffraction at an acoustic frequency of 130 MHz in a 2.0-μm ZnO-film optical waveguide with a strain-controlling film of a 1.5-μm-thick fused-quartz film, as predicted by the theory.