SPECTRAL MEASUREMENT OF THE FILM-SUBSTRATE INDEX DIFFERENCE IN PROTON-EXCHANGED LINBO3 WAVE-GUIDES

We report the spectral characterization of proton-exchanged Lithium ni obate (PE:LiNbO3) waveguides in terms of the variation of the refracti ve-index difference between the waveguiding layer and the substrate. T he dispersion of the extraordinary refractive-index increase (delta n( e)) is measured from 405 to 1319 nm with several light sources. Two ty pes of proton-exchanged waveguide, prepared under different conditions , are studied. These measurements should be of use in the optimization of PE:LiNbO3 waveguides for nonlinear optical applications, particula rly in second-harmonic generation in the blue-green wavelength region. (C) 1998 Optical Society of America.