Optical properties of aligned carbon nanotube mats for photonic applications

We studied the optical properties of the aligned carbon nanotube (16, 0), (10, 0), and (8, 4) mats for photonic device applications. We employed ab initio density functional potentials and utlized the linear combination of atomic orbital formalism. We calculated the electronic structure of the carbon nanotube mats and the real and imaginary parts of the dielectric functions as functions of the photon energy. The calculated dielectric functions of the aligned carbon nanotube mats show a strong anisotropy when the electric field of the light is parallel or perpendicular to the tube axes. Especially, there are strong peaks in the imaginary part of the dielectric function near the absorption edges, when the electric field of the light is parallel to the carbon nanotube axes. The unusual optical properties of the semiconducting carbon nanotube mats present an opportunity for applications in electro-optical devices in the infrared energy region.