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- resonant waveguide ( 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.