Optical transmission theory for metal-insulator-metal periodic nanostructures

Abstract

A semi-analytical formalism for the optical properties of a metal-insulator-metal periodic nanostructure using coupled-mode theory is presented. This structure consists in a dielectric layer in between two metallic layers with periodic one-dimensional nanoslit corrugation. The model is developed using multiple-scattering formalism, which defines transmission and reflection coefficients for each of the interface as a semi-infinite medium. Total transmission is then calculated using a summation of the multiple paths of light inside the structure. This method allows finding an exact solution for the transmission problem in every dimension regime, as long as a sufficient number of diffraction orders and guided modes are considered for the structure. The resonant modes of the structure are found to be related to the metallic slab only and to a combination of both the metallic slab and dielectric layer. This model also allows describing the resonant behavior of the system in the limit of a small dielectric layer, for which discontinuities in the dispersion curves are found. These discontinuities result from the out-ofphase interference of the different diffraction orders of the system, which account for field interaction for both inner interfaces of the structure.

Unidirectional reflectionless light propagation at exceptional points

“…Tuning the geometry rather than the refractive index can reduce the difficulty in the experimental realization of such structures. Among different plasmonic waveguide structures, MDM plasmonic waveguides are of particular interest [108][109][110][111][112][113][114][115][116], because they support modes with deep subwavelength scale over a very wide range of frequencies extending from DC to visible [117] and are relatively easy to fabricate [118,119]. The waveguide widths w, w 1 , and w 2 are set to be 50, 20, and 100 nm, respectively ( Figure 9A).…”

Electrically tunable polarization-insensitive MIM plasmonic metasurface operating in transmission mode

“…MIM plasmonic resonator typically comprises a metal resonator on top and a metal reflector/mirror at the bottom with a dielectric film sandwiched between. If the resonance is strong enough, the incident light would experience multiple reflections between the two metal films and is absorbed, mostly due to the ohmic loss of the metal films [36]. This structure can only work in the reflection mode metasurfaces since the back reflector is designed thick enough to reflect all the incident light, resulting in zero transmission.…”