Metallic Sb/GaAs core/shell nanowire as cold anti-reflective coating for optical fibres

Abstract

Of late, metallic nanowires (NWs) are gaining much interest as alternative coating materials for various optical fibres and lenses. In the present study, a first principles based approach was employed to calculate the electronic band structures, total and partial density of states (TDOS and PDOS) and various optical characteristics of Sb/GaAs core/shell (c/s) NW. The exterior atoms of the c/s NW were passivated with hydrogen atoms to prevent the occurrence of dangling bonds. The band structure showed metallic characteristic of the NW, using generalized gradient approximation (GGA). The TDOS and PDOS calculations predict that the metallic nature is due to the contributions by the Sb-5p states at the Fermi level. The refractive index (R.I.) values in the visible (VIS) region were in the range of the R.I. values for the case of flint glass, enabling the use of these NW arrays as coating materials for various optical lenses. The low absorbance values in the infrared (IR) region, coupled with reflectance intensities much less than some traditional glass mirrors, suggest the possible applications of these NWs as cold anti-reflective coating materials for optical fibres and cables.