THE REFRACTIVE-INDEX DISTRIBUTION N(C)(Z) OF ION-IMPLANTED KNBO3 WAVE-GUIDES

We have analysed by means of dark and bright light spectroscopy the c- polarised mode spectra of KNbO3 planar wave,guides. These waveguides w ere fabricated by He+ ion implantation with ion doses from 2.5 X 10(14 ) to 3 X 10(15) cm(-2) and ion energies from 1 to 2.9 MeV. A quantitat ive model is derived to correlate the index profile of n(c) with the i mplantation parameters. The results are in excellent agreement with pr ofiles observed by measuring the surface reflectivity of wedge polishe d samples. The test of the mode spectra after partial surface strippin g by ion sputtering does not evidence irregular structures in the inde x profile.