Thermal emission from layered structures containing a negative-zero-positive index metamaterial

Motivated by the realization of the optical Dirac dispersion in the homogenous negative-zero-positive index (NZPI) material, we make a theoretical investigation on the properties of thermal emission in layered structures containing the NZPI medium. We find that when the thermal emission frequency is close to the Dirac point of the NZPI medium, the spectral hemispherical power of thermal emission in such a structure is strongly suppressed and the emission can become a high directional source with large spatial coherence.