Abstract

The use of the solgel process in the fabrication of single-mode planar waveguides is described. A processing procedure has been developed to produce low loss, isotropic amorphous thin films using spin deposition of an SiO₂-TiO₂ coating solution synthesized at the Arizona Materials Laboratory at the University of Arizona. Prism coupler techniques are used to optically characterize the films. We have measured film refractive indices from 1.74 to 1.76, film thicknesses from 120 to 250 nm, and attenuation coefficients <1 dB/cm. The ability to emboss complex submicron surface features onto these films during processing makes the solgel preparation technique particularly attractive for the inexpensive fabrication of integrated optic components and devices. An embossing technique has been developed to fabricate waveguide grating couplers onto the surfaces of the SiO₂-TiO₂ films. We have measured peak-to-trough modulation depths of 25-45 nm for embossed blazed gratings of 1.6-µm period. Input and output coupling efficiencies are presented. For films embossed immediately after spin coating, grating depths shrink to ~57% of their preheattreatment depth. No lateral grating shrinkage is observed.

© 1989 Optical Society of America