Characterization of power absorption response of periodic three-dimensional structures to partially coherent fields

Abstract

In many applications of absorbing structures it is important to understand their spatial response to incident fields, for example in thermal solar panels, bolometric imaging and controlling radiative heat transfer. In practice, the illuminating field often originates from thermal sources and is only spatially partially coherent when reaching the absorbing device. In this paper, we present a method to fully characterize the way a structure can absorb such partially coherent fields. The method is presented for any 3D material and accounts for the partial coherence and partial polarization of the incident light. This characterization can be achieved numerically using simulation results or experimentally using the Energy Absorption Interferometry (EAI) that has been described previously in the literature. The absorbing structure is characterized through a set of absorbing functions, onto which any partially coherent field can be projected. This set is compact for any structure of finite extent and the absorbing function discrete for periodic structures.

Realizing efficient THz circular dichroism using ultra-thin chiral metasurface

“…The maximum achievable absorption is 87%, with a CD of approximately 70% at a wavelength ranging from 1.3 μm to 1.8 μm with high-contrast chiral reflective images. A bilayer design with remarkable selectivity for RCP and LCP wave absorption is proposed in [31]. Recently a plasmonic chiral metamaterial with T-shaped, I-shaped, and E-shaped structures stacked in a particular way has been used to build a bilayer for terahertz applications with high circular dichroism and considerable optical activity [32][33][34][35][36].…”

General relation between spatial coherence and absorption

“…He considered the absorption by a body illuminated by two deterministic phase-locked monochromatic sources located at two points r 1 , r 2 which generate an interference pattern in the absorbing body. To account for the effect of interferences on absorption, Rytov introduced a complex tensor quantity, the "mixed losses" [12][13][14][15], which can be measured experimentally [16,17]. Rytov showed that, for incandescent emitters at uniform tem-perature, the cross-spectral density tensor of the fields is directly proportional to the complex conjugate of the mixed losses [12].…”