Guided modes in anisotropic metal bound waveguides

The dispersion relation determining guided modes in electro-optic (EO) waveguides sandwiched by metallic ground- and cover-layer electrodes has been deduced. The metal generally has a complex dielectric constant ε = ε′ + iε′′, with ε′ < 0 and ε′′ > 0. It is shown that for the reflection at a waveguide/metal interface, when −ε′ ≫ ε′′, the phase shifts on the reflection for TE- and TM-guided waves have opposite signs. This in turn results in a significant modification to waveguide dispersion characteristics and leads to an unusual phenomenon in the guided waves: under some conditions, the metal bound waveguides support higher-order guided modes, but may not allow guiding of the fund-amental and/or lower-order modes. This revised version was published online in November 2006 with corrections to the Cover Date.