The influence of the inner structure of CNT forest metamaterials in the infrared regime

Electrically anisotropic one-dimensional materials, like carbon nanotubes (CNTs), have high potential to become substitutes to conventional metamaterials made of metals, and to overcome their limitations. The exceptional properties of CNT metamaterials are to be expected, mainly due to the anisotropic optical and electrical properties of the CNTs, which behave like one-dimensional nanorod antennas in the electromagnetic radiation. In this work, the infrared properties of novel CNT forest metamaterials, prepared on the patterned catalyst film are presented. The influence of the inner structure of CNT forest metamaterials, such as an orientation (horizontal and vertical), density and alignment of CNTs within the forest, are studied for the first time, in the non-polarized infrared light. The investigation of the phenomena responsible for changes of the total IR reflectance and transmittance of the patterned CNTs was carried out and showed the decrease of the total reflectance and transmittance with the improvement of the density and the alignment. Furthermore, the simulation of the anisotropic behavior of patterned CNT forest, and SRR orientation towards the electric field E were investigated for the first time and showed major changes in the transmittance, with the lowest values of transmittance achieved for y-axis anisotropy and perpendicular orientation of the SRR to the E field. Simulation results showed for the first time, that the effect of anisotropic structure can be stronger than the effect of the SRR orientation.