Modeling of Optical Properties of Nanosize Metal—Dielectric Gratings within the Eigenmode Approach

摘要

We show that the wide-spread concept of optical eigenmodes in lossless waveguide systems, which assumes the separation into propagating and evanescent modes, has to be revised in the case of metal-dielectric structures. In addition, there exists a sequence of new eigenstates with complex values of the propagation constant. Taking these anomalous modes into account we have developed an original approach for the modeling of optical properties of subwavelength metal gratings with nanosize slits. The obtained spectra of transmittance and reflectance demonstrate the application potential of such structures for efficient spectral filtration of optical signals.