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Metasurfaces have emerged as elegant engineered interfaces capable of controlling optical phases and amplitudes within ultra-flat form factors. Recently, there has been an increasing effort to achieve reconfigurable metasurfaces incorporating various tuning mechanisms, including electrical, optical, mechanical or thermal driving forces. In particular, electronic tuning has previously been shown to provide potential control over virtually a full range of optical phases. However, practical implementation is limited by the maximum doping that can be achieved by applying bias, and by the inherent losses of the constituent materials. In this work, we apply electrically-tuned reconfigurable metasurfaces to achieve dynamically-controlled thermal sources. Kirchhoff’s law of thermal radiation suggests possible active control of spectral and angular properties of radiated heat in carefully designed metasurfaces. This goal can be achieved by coupling optical resonances that imply spectral and angular selectivity, to 2D plasmonic resonances in active structured 2D surfaces. We discuss the potential of different 2D materials, such as graphene, black phosphorus and transition metals dichalcogenides, with respect to their respective optical properties, bandgaps and inherent losses. The ultimate goal is to achieve maximal absorption in a dynamically selected direction at a given wavelength, by exciting surface-confined modes. Enabling active beam steering of coherent thermal sources may provide low-cost alternatives to existing infrared sources for applications such as sensing and thermal management.
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