MASKING PROBLEM IN THE FABRICATION OF OPTICAL WAVE-GUIDE STRUCTURES IN GLASS BY DOUBLE ION-EXCHANGE

Different metal and dielectric films are studied as masking films for the fabrication of optical waveguide structures in glass substrates bg double ion exchange. The metal (Al, Ti, and Pt) films with thickness 0.5-1.0 mu m and inorganic dielectric films (SiO2, Si3N4, and Al3O3) w ith thickness 0.2-0.5 mu m have piercing defect densities higher than 2 x 10(2) cm(-2) and are not suitable for masks. For the first time po lyimide and high temperature silicon tarnish films are proposed for ma sks, as no pinholes or other piercing defects are found in them. The a dvantage of the polyimide films is demonstrated by the preparation of thin film homogeneous refracting waveguide lenses free of any highly s cattering centers.