Engineering and Controlling Optical Tamm States Confined at Plasmonic Metasurfaces

We demonstrate experimentally that optical Tamm states corresponding to Tamm plasmons can be supported by a dielectric mirror interfaced with a metasurface, a discontinuous thin metal film periodically patterned on the sub-wavelength scale. Not only do such states survive the nano-patterning of the metal film, but they also become sensitive to external perturbations, as a result. In particular, by depositing a nematic liquid crystal on the outer side of the metasurface we were able to red-shift Tamm plasmons by 35 nm, while electrical switching of the liquid crystal enabled us to tune the wavelength of these notoriously inert excitations within a 10 nm range.