Optical properties of multilayer metal-dielectric nanofilms with all-evanescent modes

We present a systematic study of mode characteristics of multilayer metal-dielectric (M-D) nanofilm structures. This structure can be described as a coupled-plasmon-resonantwaveguide (CPRW), a special case of coupled-resonator optical waveguide (CROW). Similar to a photonic crystal, the M-D is periodic, but there is a major difference in that the fields are evanescent everywhere in the M-D structure as in a nanoplasmonic structure. The transmission coefficient exhibits periodic oscillation with increasing number of periods. As a result of surface-plasmon-enhanced resonant tunneling, a 100% transmission occurs periodically at certain thicknesses of the M-D structure, depending on the wavelength, lattice constants, and excitation conditions. This structure indicates that a transparent material can be composed from non-transparent materials by alternatively stacking different materials of thin layers. The general properties of the CPRW and resonant tunneling phenomena are discussed.