Linear and Nonlinear Optical Properties of Annealed Proton Exchanged Lithium Niobate Waveguides,
Abstract
Annealed proton exchange (APE) is an important technique for the fabrication of waveguides in LiNbO3 for electrooptic and nonlinear optical applications. Unannealed proton exchanged (PE) waveguides have step-like refractive index profiles and large extraordinary refractive index changes, but suffer from reduced electrooptic and nonlinear coefficients. Post-exchange annealing is necessary to produce single mode waveguides that exhibit electrooptic and nonlinear optical properties comparable to bulk LiNbO3 and low insertion loss in fiber optic applications. While the PE process is well-characterized, quantitative modeling of APE waveguides is much less well developed. In this paper we present measurements of the effective mode indices and fundamental mode profiles for APE waveguides subjected to a variety of exchange and annealing conditions in both x- and z-cut substrates, along with empirical models for the concentration-dependent diffusion coefficient and dispersion that allow accurate calculation of the refractive index profile for APE waveguides as a function of exchange depth and anneal time for wavelengths between 0.4 and 1.1 micrometer. The reduction of the nonlinear susceptibility in PE waveguides, measured by a reflected second harmonic generation technique, is also discussed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1992
- Accession Number
- ADP008075
Entities
People
- M. L. Bortz
- M. M. Fejer
Organizations
- Stanford University