Importance of shadowing and multiple reflections in emission polarization

Abstract

Polarization characteristics of thermal radiation emitted from surfaces are investigated within the geometrical optics approximation. Analytical results are presented for photons emitted without subsequent reflection from surfaces having sawtooth corrugations with different slope distributions. Analytical results are used to validate a Monte Carlo simulation designed to determine and quantify the effects of multiple reflection of emitted photons from surface structures and, in addition, to treat two-dimensional surfaces. Results are shown that illustrate the dependence of the degree of polarization on the relative orientation of the viewing angle with respect to the corrugations. Simulations of emission from structured and random two-dimensional surfaces show that, whilst the total emission can saturate, the degree of polarization decreases with increasing roughness of the surface morphology. The prospect for manipulating surfaces to have specific polarization signatures is discussed.