Low-voltage drive electro-optic Pb(Zr,Ti)O3 waveguide devices fabricated by solid-phase epitaxy

Pb(Zr,Ti)O3 (PZT) thin film optical waveguides were grown on Nb-doped SrTiO3(100) substrates by solid-phase epitaxy to fabricate an electrode/waveguide/semiconductor structure. The substrates were spin-coated with methoxyethoxide precursor solutions and preannealed to form amorphous thin films followed by the solid-phase epitaxial crystallization of the thin films above 650 degrees Celsius. The grown epitaxial PZT waveguides had a single perovskite phase and a single (001) orientation. The propagation loss was reduced to 1.7 dB/cm by introducing an epitaxial buffer layer between the PZT waveguide and the Nb-doped SrTiO3 substrate. An electro- optic beam deflector was fabricated by sputtering an ITO prism electrode on the surface of the waveguide. Efficient laser beam deflection larger than 10 mrad was observed by applying 5 V between the prism electrode and the substrate. An index change higher than 0.001 at 5 V and an effective electro-optic coefficient larger than 40 pm/V were estimated from the deflection characteristic. For integrating the electro-optic PZT waveguide devices with passive waveguide components, channel waveguides and waveguide lenses were also fabricated in the PZT waveguides using a simple wet-etching process. These achievements suggest the realization of variety of low- voltage drive integrated waveguide devices including matrix switches as well as the deflectors.