AVS 47th International Symposium
    Photonics Tuesday Sessions
       Session PH-TuA

Invited Paper PH-TuA4
Processing of (Pb,La)(Zr,Ti)O@sub 3@ Waveguide Devices on Nb-doped SrTiO@sub 3@ by Solid-phase Epitaxy

Tuesday, October 3, 2000, 3:00 pm, Room 310

Session: Challenges in Photonics Materials and Device Processing
Presenter: K. Nashimoto, Fuji Xerox Co., Ltd., Japan
Authors: K. Nashimoto, Fuji Xerox Co., Ltd., Japan
H. Moriyama, Fuji Xerox Co., Ltd., Japan
K. Haga, Fuji Xerox Co., Ltd., Japan
M. Watanabe, Fuji Xerox Co., Ltd., Japan
E. Osakabe, Fuji Xerox Co., Ltd., Japan
S. Nakamura, Fuji Xerox Co., Ltd., Japan
T. Morikawa, Fuji Xerox Co., Ltd., Japan
Correspondent: Click to Email
It is very attractive to utilize (Pb,La)(Zr,Ti)O@sub 3@ (PLZT) ferroelectric materials for optical waveguide devices because of their excellent electro-optic properties. It is also of great interest to fabricate an electrode/ferroelectric waveguide/electrode structure since a narrow electrode gap resulting in a low-voltage drive will be achieved as compared with conventional LiNbO@sub 3@ waveguide devices which have coplanar electrodes. For realizing the structure, epitaxial PLZT thin films are able to be grown on Nb-doped SrTiO@sub 3@ (Nb:ST) semiconductor substrates. However, it has been difficult to prepare a low-loss PLZT waveguides by vapor phase growth techniques. While, we demonstrated the growth of a heterostructure waveguide consisted of a PZT waveguide layer and a PLZT buffer layer on a Nb:ST substrate by solid-phase epitaxy. The PLZT buffer layer was introduced to avoid absorption loss by the substrate. The solid-phase epitaxy is a simple and useful process in terms of stoichiometric composition control, uniform large-area fabrication, low-loss capability, and waveguide patterning. The substrates were spin-coated with methoxyethoxide precursor solutions, preannealed to form amorphous thin films, and annealed to promote the solid-phase epitaxial crystallization of the thin films. The propagation loss in the grown epitaxial PLZT heterostructure waveguides was less than 1 dB/cm. Effective electro-optic coefficients as large as 40 pm/V and polarization insensitive properties were confirmed. A simple wet-etching process followed by the solid-phase epitaxy was developed for making 5 µm-wide channels in the PLZT waveguides. Digital matrix switches fabricated by the wet-etching and the solid-phase epitaxy showed low propagation losses and low-voltage responses.