Metamaterials for visible and near infrared antireflective properties and large surface elaboration

We propose two distinctive designs of metamaterials demonstrating antireflective properties in the optical and near infrared region and, simultaneously, a high reflectivity in the mid-infrared. Since the emissivity is related to the absorption of a material, our structures would then offer a high emissivity in the visible and near infrared. Beyond those wavelengths, the emissivity would be quite low. Usually, such systems find their applications in the field of thermophotovoltaics, where the goal is to convert radiation from the visible up to 2.5 microns into electrons, while limiting the emissivity for the larger wavelengths. A particular interest in the field of optoelectronics is found as well, especially for optical detection. Here, the major difficulty is to offer a metal thick enough to be considered as mirror across the electromagnetic radiation spectrum that possesses at the same time an anti-reflective character within a range of several microns. Thus, we have summoned the exceptional physical properties of the material patterning. Numerical analysis has been performed on commonly used metamaterial designs: a perforated metallic plate and a metallic cross grating. Through all these structures, we have demonstrated the various physical phenomena contributing to a reduction in the reflectivity in the optical and near infrared region. By showing realistic geometric parameters, the structures were not only designed to demonstrate a good optical response but were also meant to be feasible on large surfaces by lithographic methods such as micro contact printing or nano-imprint lithography.