Acrobatics for thermal emission using metastructures

In high temperature and vacuum applications, for which heat transfer is predominantly by radiation, the material's surface texture is of substantial importance. Control of thermal emission is of crucial concern in the design of infrared sources, in electronic chip coolants, in high-efficiency photovoltaic cells, and in solar energy conversion. Thermal emission has been shown to be modified by utilizing the high density of states of surface waves (surface plasmon polaritons and surface phonon polaritons) and their long-range propagation. We present subwavelength structures - metastructures supporting surface waves for obtaining polarization manipulation of thermal emission, extraordinary coherent thermal radiation, bandgap in the spectral emission, and a broadband infrared absorption. A spin-dependent dispersion splitting was obtained in a structure consisting of a coupled thermal antenna array. The effect is due to a spinorbit interaction resulting from the dynamics of the surface waves propagating along the structure whose local anisotropy axis is rotated in space. The dispersion splitting due to the spin-orbit coupling is also known as the key feature in such remarkable effects as the Rashba splitting and the spin-Hall effect, which indicates the generic nature of the discussed phenomenon. The observation of the spin-symmetry breaking in thermal radiation paves the way to manipulate spontaneous emission with the photons' intrinsic degree of freedom and provides the basis for future spinoptics devices.