A geometric Doppler effect manifested by a spin-split dispersion relation of thermal radiation is observed. A spin-dependent dispersion splitting was obtained in a structure consisting of a coupled thermal antenna array. The effect is due to a spin-orbit interaction resulting from the dynamics of the surface waves propagating along the structure whose local anisotropy axis is rotated in space. The observation of the spin-symmetry breaking in thermal radiation may be utilized for manipulation of spontaneous or stimulated emission.

We demonstrate an extraordinary quasimonochromatic thermal emission with high spatial coherence length (lc>2400λ) and a quality factor Q=2320 at radiation frequencies that are much smaller than the plasma frequency of metal (ω≪ωp). This emission is achieved by forming a plasmonic bandgap, which is obtained by a periodic structure on a metallic surface. Such a structure modifies the dynamics of the surface wave and results in a van Hove singularity [Van Hove, Phys. Rev. 89, 1189 (1953)] in the spectral density of states while maintaining a large coherence length.

No abstract

Space-variant polarization manipulation of enhanced nondirectional thermal emission in a narrow spectral peak is presented. The emission is attributed to surface phonon-polariton excitation from space-variant subwavelength SiO2 gratings. Polarization manipulation was obtained by discretely controlling the local orientation of the grating. We experimentally demonstrated thermal emission in an axially symmetric polarization distribution. Theoretical calculations based on rigorous coupled-wave analysis are presented along with experimental results.

In high temperature and vacuum applications, when heat transfer is predominantly by radiation, the material’s surface texture is of substantial importance. Several micro- and nanostructure designs have been proposed to enhance a material’s emissivity and its radiative coherence, as control of thermal emission is of crucial concern in the design of infrared sources, optical filters, and sensing devices. In this research, an extraordinary coherent thermal emission from an anisotropic microstructure is experimentally and theoretically presented. The enhanced coherency is due to coherent coupling between resonant cavities obtained by surface standing waves, wherein each cavity supports a localized field that is attributed to coupled surface phonon polaritons. We show that it is possible to obtain a polarized quasimonochromatic thermal source from a SiC microstructure with a high quality factor of 600 at the resonant frequency of the cavity and a spatial coherence length of 716 wavelengths, which corresponds to an angular divergence of 1.4mrad. In the experimental results, we measured a quality factor of 200 and a spatial coherence length of 143 wavelengths. We attribute the deviation in the experimental results to imperfections in the fabrication of the high quality factor cavities.