Waveguides for Integrated Optics Formed by Metal Platings

Theoretical analyses and performance results are presented for two waveguides for integrated optics which are formed by metal platings, employing structures similar to those in some modulators or switches. One structure is a slot waveguide, formed by a slot or gap of unplated film on a substrate between two plated regions, for which previous analyses are incorrect for one polarization. The correct analysis shows that for that polarization the modes are leaky and that propagation occurs over a wider frequency range than expected. The other structure is a new one consisting simply of a strip of metal plated on a film on a substrate. Waveguiding with low loss is possible under appropriate conditions because metals at optical frequencies behave as overdense plasmas.