Grating-coupled excitation of Tamm waves

We formulated a boundary-value problem for the excitation of Tamm waves guided by the periodically corrugated interface of a homogeneous material and a rugate filter. Both partnering materials are isotropic and dielectric. After solving the problem using the rigorous coupled-wave approach, the total transmittance, total reflectance, and absorptance were calculated as functions of the angle of incidence of a plane wave that could be either p or s polarized. The excitation of a Tamm wave was inferred for every absorptance peak that is independent of the thicknesses of both partnering materials. Therefore, multiple Tamm waves can be simultaneously excited using a converging or diverging incident beam instead of an incident plane wave. Even though the absorptance peaks are very low when a Tamm wave is excited, the corresponding spikes in the total-reflectance curves are much larger and guarantee experimental detection, as well as application to optical sensing.