Abstract: An optical absorber includes vertically aligned carbon nanotubes with an ultra-low reflectance less than 0.16% and an absorption efficiency greater than 99.84%. The index of refraction and the absorption constant are controlled by independently varying the nanotube diameter and nanotube spacing. The nanotubes are mostly double-walled. The density of the nanotube arrays is very low, around 0.015 g/cm3.

Abstract: A light source is provided by a photonic crystal having an enhanced photonic density-of-states over a band of frequencies and wherein at least one of the dielectric materials of the photonic crystal has a complex dielectric constant, thereby producing enhanced light emission at the band of frequencies when the photonic crystal is heated. The dielectric material can be a metal, such as tungsten. The spectral properties of the light source can be easily tuned by modification of the photonic crystal structure and materials. The photonic crystal light source can be heated electrically or other heating means. The light source can further include additional photonic crystals that exhibit enhanced light emission at a different band of frequencies to provide for color mixing. The photonic crystal light source may have applications in optical telecommunications, information displays, energy conversion, sensors, and other optical applications.