Near-Field Thermal Emission of Thin Films

While the far-field thermal emission of thin film have been described in detail during the last five years [1–2], surprisingly, no systematic study on their near-field emission has been carried out so far. In this work we present an exact calculation of the local density of state of the non-radiative part of electromagnetic field close to the surface of thin metallic films. We describe the specific near-field properties of bounded structures. In particular it is found that this density closely depends on the thickness of films and can be significantly greater than that of near-field at the same distance from a semi-infinite medium. These results should have important consequences in the design of planar near-field thermal sources.