Taming the thermal emissivity of metals: A metamaterial approach

We demonstrate the possibility of realizing temporally coherent, wide-angle, thermal radiation sources based on the metamaterial properties of metallic gratings. In contrast to other approaches, we do not rely on the excitation of surface waves such as phonon-polaritons, plasmon-polaritons, or guided mode resonances along the grating, nor on the absorption resonances of extremely shallow metallic grating. Instead, we exploit the effective bulk properties of a thick metallic grating below the first diffraction order. We analytically model this physical mechanism of temporally coherent thermal emission based on localized bulk resonances in the grating. We validate our theoretical predictions with full-wave numerical simulations.