Metal-clad planar dielectric waveguide for integrated optics*

Attenuation characteristics of a metal-clad four-layer thin-film optical waveguide are presented. Guided-wave losses are calculated as functions of isolation-layer thickness, type of metal, and isolation-layer refractive index. The TM polarized waves were found to exhibit an absorption peak as a function of isolation thickness. This peak is interpreted as resonant coupling to a lossy surface-plasma wave.