A study, using nuclear techniques, of waveguides produced by electromigration processes

Nuclear techniques, such as Rutherford backscattering spectrometry and nuclear reaction analysis, have been extensively used in the near-surface analysis of glass. They provide a nondestructive analytical method, with high depth resolution and without radiation effects induced by the analyzing beam. In particular, the authors used nuclear techniques for the analysis of chemical and physical processes involved in optical guide formation. Optical waveguides were produced by using electromigration from metallic films, and a comparison was made with ion-exchange processes. A systematic study of the mechanisms which govern the in-depth migration of Ag, Au, and Cu ions in glasses, in the presence of an external field, was performed in order to create buried waveguides. Metallic films were evaporated on the surface of glasses of different composition. Electric fields, ranging from 300 to 1000V/cm, were applied across the glasses for different times and temperatures. The metal ion distribution and glass composition modifications were analyzed. Theoretical and experimental profiles have been compared, and the importance of the different parameters (electric field, glass temperature, metal surface layer thickness, process duration) have been highlighted. The electromigration technique was also applied for the formation of strip waveguides.