Properties of thermal radiation in photonic crystals

We analyze the properties of the thermal radiation in photonic crystals and show that the spectral energy density, the spectral intensity, and the spectral hemispherical power are only limited by the total number of photonic states available. Due to the possible presence of photonic band gaps and the associated spectral redistribution of photonic states, it is possible to have spectral regions over which the thermal radiation generation and propagation are completely inhibited or strongly enhanced relative to the corresponding free space or homogeneous dielectric medium blackbody limits. Using a differential geometry approach, we also investigate the directional properties of the thermal radiation propagation in photonic crystals and analyze the thermal photon focusing effects that take place in these systems.