《plasmonic_wire_grating》.pdf

Solved with COMSOL Multiphysics 4.1 Plasmonic Wire Grating Introduction A plane electromagnetic wave is incident on a wire grating on a dielectric substrate. The model computes transmission and reflection coefficients for the refraction, specular reflection, and first order diffraction. Model Definition Figure 1 shows the considered grating, with a gold wire on a dielectric material with refractive index nβ. The grating constant, or the distance between the wires, is d . A plane-polarized wave traveling through a medium with refractive index nα is incident on the grating, at an angle α in a plane perpendicular to the grating. n α α Au d nβ Figure 1: The modeled grating. The model considers a unit cell of a slice through this geometry. The grating is assumed to consist of an infinite number of infinitely long wires. If the wavelengths involved in the model are sufficiently short compared to the grating constant, one or several diffraction orders can be present. The diagram in Figure 2 P L A S M O N I C W I R E G R A T I N G | 1 Solved with COMSOL Multiphysics 4.1 shows two transmissive paths taken by light incident on adjacent cells of the grating, exactly one grating constant apart. d sin(α) α