Harvesting the electromagnetic energy confined close to a hot body

Abstract

In the close vicinity of a hot body, at distances smaller than the thermal wavelength, a high electromagnetic energy density exists due to the presence of evanescent fields radiated by the partial charges in motion around its surface. This energy density can surpass the energy density in vacuum by several orders of magnitude. By approaching a PV cell with a band gap in the infrared frequency range this non-radiative energy can be transferred to it by photon tunneling and surface mode coupling. Here we review the basic ideas and recent progress in near-field energy harvesting.