Abstract

Thin silica-titania planar waveguides doped with cadmium sulphide have been prepared on fused silica substrates using the sol-gel technique. Tetraethoxisylane (TEOS) and titanium butilate Ti(n-OBu)₄ (30%) were used as precursors of the film.¹ The semiconductor dopants have been introduced by adding cadmium nitrate and thiourea to the starting solution as precursors of cadmium and sulphur, respectively. The films have been produced by dipping the samples in the solution and withdrawing them at constant speed. Thereafter the samples have been densified at 300°C for 4 hours in nitrogen atmosphere in order to prevent outdiffusion of the dopants. The thickness of the films is typically about 1300 A and their refractive index is 1.63 at 633 nm.

© 1994 IEEE