Analysis of emissivity and absorptivity of two overlapping guided modes in two-dimensional periodic structures

Abstract

The thermal emission from two guided modes in two-dimensional periodic structures is investigated using first-principles calculations. We use a model that integrates a quantum mechanical analysis of light-matter interactions and a classical connection condition that describes the coupling between light modes inside and outside the structure. We focus on what happens when two guided modes share common radiation modes where their thermal emission overlaps in frequency, solid angle, and polarization in free space. It is shown that we have to take into account the fact that the reaction of the radiation from one guided mode works not only on that guided mode but also on the other guided mode, in order to calculate the emissivity from two overlapping guided modes accurately. Emissivity spectra peculiar to the two-guided mode cases are shown. The condition to maximize the light-matter interaction with respect to thermal emission in the case with two guided modes is also discussed.