Surface electromagnetic waves supported by the interface of two semi-infinite rugate filters with sinusoidal refractive-index profiles

The canonical problem of surface-wave propagation guided by the interface of two semi-infinite rugate filters made of isotropic dielectric materials was formulated and solved. Numerical studies showed that multiple Tamm waves-with different phase speeds, polarization states, and degrees of localization-can be guided by the interface of a homogeneous dielectric material and a rugate filter. Multiple Tamm waves and optical Tamm states are supported by a phase-defect interface in a rugate filter. A sudden change of either the mean refractive index or the amplitude of the sinusoidal variation of the refractive index also creates an interface that can guide multiple Tamm waves, as can the interface of two distinct rugate filters. Whereas the Tamm waves can be either p or s polarized, all optical Tamm states were found to be p polarized.