Abstract

The formation of thin films from solutions by dip-coating is a well-known method for the fabrication of optical waveguides. We have developed a procedure with which tapers and lenslike regions in a planar waveguide can be obtained by solution deposition. Using a microprocessor controlled dipping arm, substrates are lowered into a commercial SiO₂:TiO₂ solution and then carefully withdrawn with a predetermined velocity pattern, which varies as a function of substrate position. As the substrate is removed from the solution, the film immobilizes almost instantly. This, along with the fact that the film thickness depends on the lifting speed, allows us to fabricate high-quality waveguides with varying thickness profiles. A single dipping yields a film with thicknesses from 0.05 to 0.15 μm; thus the structures are typically single mode. Multimode waveguides can be made by repeated dippings. We report on the tapered waveguides that have been fabricated and also describe the fabrication and properties of lenslike waveguides, which focus guided rays with an effective gradient produced by the thickness profile.

© 1987 Optical Society of America