Control of Near-Field Emitted by Micro and Nanostructured Materials

Progress in synthesis technologies of micro and nanocomposite materials has opened the way to the control of electromagnetic field these media spontaneously emit in their surrounding. If numerous nanostructured materials [1–3] have been designed during the last decade to control both spectrally and directionally the far (propagative) field that they radiate in their surrounding, very few attention has been paid so far to the control of non-radiative field which exponentially decreases from their surface. However, such control is very important to improve the performance of numerous near-field technologies such as the plasmon assisted nanophotolitography [4], the near-field spectroscopy [5] and to develop new energy conversion technologies such as the near-field thermophotovoltai¨c energy conversion [6]. The near field properties of micro and nanostructured materials are closely conditioned by the presence, hybridization and coupling of localized modes within the structure. These modes come from the presence of collective oscillations of free electrons in metallic compounds or from the vibrations of partial charges carried out by atoms in polar materials. In this paper we present an approach we have recently developed [7] to design micro and nanolayered thermal sources with a tailored near-field emission spectrum and we briefly discuss the basic physical mechanisms involved in these modifications of field.