Design and Fabrication of BaTiO<sub>3</sub> Crystal Thin-Film Waveguides

Abstract

BaTiO3 crystal film has the very high electro-optic effect, so it has important research value for thin film waveguide electro-optic modulators. In this work, BPM software is used to simulate the single-mode condition of ridge waveguide at first, then BaTiO3 film waveguide structure is designed with suitable film thickness.BaTiO3 waveguide thin films are grown by pulsed laser deposition on single crystal MgO substrate. The BaTiO3 thin-film crystalline structures grown at different temperature sand different laser powers were analyzed by using X ray diffraction , which showed the BaTiO3 films have a priority crystallization direction and good crystallization quality at 750°C grown temperature. For the optimally-designed waveguide structures, the PECVD technique and ICP plasma etching method are employed to coat and etch Si3N4 films, respectively. Through the optimization of main process parameters, 60 sccm reaction gas flow and 150 nm/min etching speed are finally selected to create the ridge waveguides, and consequently, the surface roughness of Si3N4 film waveguide reaches 2.3 nm.