Improving the acousto-optical interaction by an introduction of a planarisation SiO2 layer

This paper introduces a planarisation SiO2 layer into the configuration of ZnO-silicon-on-insulator for constructing an acoustical resonant cavity to enhance the acoustic density on a silicon-on-insulator waveguide. The improved configuration with a planarisation SiO2 layer can increase the acousto-optical interaction by about three times and 20% compared with acousto-optical configuration of ZnO pads only in an interdigital transducer region and all over a silicon on insulator. Moreover, an introduction of a planarisation SiO2 layer can reduce acoustic reflection on optical waveguide and optical waveguide loss for an acousto-optical device on silicon-on-insulator optical waveguides.