Modified thermal radiation in three-dimensional photonic crystals

Thermal radiation from an empty blackbody cavity follows the conventional Wien’s displacement law. At a temperature $T=2500\mathrm{}\mathrm{K},$ the maximum monochromatic radiation intensity lies at a wavelength of $1.16\mu \mathrm{m},$ and radiation into the visible band occupies only 3% of the total radiation energy. In this paper, we show that when the cavity is filled with a three-dimensional photonic crystal, a strong thermal radiation band can appear in the visible regime, significantly improving the luminescence efficiency. This is attributed to the redistribution of photon density of states (DOS) in different frequency ranges in the photonic crystal leading to orders-of-magnitude enhancement of DOS in the visible wavelength over that in the infrared wavelengths.