Manipulating thermal emission with spatially static fluctuating fields in arbitrarily shaped epsilon-near-zero bodies

The control and manipulation of thermal fields is a key scientific andtechnological challenge, usually addressed with nanophotonic struc-tures with a carefully designed geometry. Here, we theoreticallyinvestigate a different strategybased on epsilon-near-zero (ENZ)media. We demonstrate that thermal emission from ENZ bodies ischaracterized by the excitation of spatially static fluctuating fields,which can be resonantly enhanced with the addition of dielectricparticles. The“spatially static”character of these temporally dynamicfields leads to enhanced spatial coherence on the surface of the body,resulting in directive thermal emission. By contrast with other ap-proaches, this property is intrinsic to ENZ media and it is not tied toits geometry. This point is illustrated with effects such as geometry-invariant resonant emission, beamforming by boundary deforma-tion, and independence with respect to the position of internalparticles. We numerically investigate a practical implementationbased on a silicon carbide body containing a germanium rod.