PLZT thin film optical waveguide devices

(Pb,La)(Zr,Ti)O₃ (PLZT) bilayer waveguides consisting of an optical waveguide layer and an optical buffer layer were grown on Nb-doped semiconductive SrTiO₃ (NST) substrates by solid-phase epitaxy. Very low propagation losses less than 0.1 dB/cm were achieved at 1.55 μm-wavelength in the PLZT slab waveguides on NST substrates. Electro-optic deflection devices were fabricated by preparing indium tin oxide transparent prism electrodes on the surface of the waveguides. Efficient deflection of laser beam coupled in the waveguides was demonstrated by applying voltage between the prism, electrodes and the substrates. Effective electro-optic coefficients as large as 45 pm/V and polarization insensitive properties were observed. A wet-etching or dry-etching process was utilized for fabricating devices with 3 to 6 μm-wide channels in the waveguides. Fabricated optical switches showed low-loss, low-voltage drive, and fast response characteristics.