Overcoming black body radiation limit in free space: metamaterial superemitter

TL;DR

This paper proposes that by using ideal double negative metamaterials, it is theoretically possible to surpass the traditional black body radiation limit, enabling super-Planckian thermal emitters and absorbers.

Contribution

It introduces a theoretical framework for creating metamaterial emitters with spectral emissivity exceeding black body limits, challenging established thermodynamic laws.

Findings

Spectral density of thermal radiation can be arbitrarily high with ideal metamaterials.

Proposes a physical realization of superemitter with super-Planckian emission.

Superemitter acts as an optimal thermal sink, outperforming black bodies.

Abstract

Here, we demonstrate that the power spectral density of thermal radiation at a specific wavelength produced by a body of finite dimensions set up in free space under a fixed temperature could be made theoretically arbitrary high, if one could realize double negative metamaterials with arbitrary small loss and arbitrary high absolute values of permittivity and permeability (at a given frequency). This result refutes the widespread belief that Planck's law itself sets a hard upper limit on the spectral density of power emitted by a finite macroscopic body whose size is much greater that the wavelength. Here we propose a physical realization of a metamaterial emitter whose spectral emissivity can be greater than that of the ideal black body under the same conditions. Due to the reciprocity between the heat emission and absorption processes such cooled down superemitter also acts as an optimal sink for the thermal radiation --- the "thermal black hole" --- which outperforms Kirchhoff-Planck's black body which can absorb only the rays directly incident on its surface. The results may open a possibility to realize narrowband super-Planckian thermal radiators and absorbers for future thermo-photovoltaic systems and other devices.