| 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/cm 3 . |