Enhanced near-field radiation in both TE and TM waves through excitation of Mie resonance

Abstract

Near-field radiative heat transfer between two bodies can exceed the far-field blackbody limitation predicted by Planck's law due to the evanescent waves tunneling or coupling of additional surface modes, which typically can occur only in TM modes for nonmagnetic materials. The Mie resonance may have the potential to enhance near-field radiation in both TM and TE modes according to the calculated results from effective medium theory. However, there is no exact solution to verify this to date. In this paper, we will give a rigorous numerical investigation of the role of Mie resonance in near-field radiative heat transfer. The framework of fluctuational electrodynamics that combines scattering matrix theory with the rigorous coupled wave analysis method is used to exactly compute the near-field radiative flux between Mie resonant dielectric cubic arrays. It shows that due to the excitation of Mie resonance, causing $\ensuremath{\varepsilon}/\ensuremath{\mu}$ near-pole effects, the radiative heat flux could be spectrally enhanced in TM/TE modes. The discrepancy between the effective medium theory and the exact method is also elucidated in detail. The findings will provide a way to control near-field thermal spectrum via all-dielectric metamaterials for emerging thermal technologies.