FABRICATION AND CHARACTERIZATION OF A CDS-DOPED SILICA-ON-SILICON PLANAR WAVE-GUIDE

A planar silica-titania waveguide doped with CdS nanocrystallites has been fabricated on a silicon substrate. A passive nanoporous host laye r and a pure silica buffer layer, of thickness 2.2 and 7.5 mu m, respe ctively, were deposited by the sol-gel technique. Crystallites were th en precipitated in the porous matrix by soaking in a CdF2 solution fol lowed by reaction in H2S gas, and a sputtered layer of silica was used to seal the structure. The absorption spectrum of an equivalent film indicates crystallites with radii up to similar to 26 Angstrom, while energy dispersion spectroscopy indicates a dopant concentration of sim ilar to 0.5 volume%. The third order optical nonlinearity (Kerr effect ) was measured using an m-line technique, yielding a value of -5 x 10( -9) cm(2)/kW.