The controlled fabrication and geometry tunable optics of gold nanotube arrays

Abstract

Arrays of vertically aligned gold nanotubes are fabricated over several square centimetreswhich display a geometry tunable plasmonic extinction peak at visible wavelengthsand at normal incidence. The fabrication method gives control over nanotubedimensions with inner core diameters of 15–30 nm, wall thicknesses of 5–15 nmand nanotube lengths of up to 300 nm. It is possible to tune the position of theextinction peak through the wavelength range 600–900 nm by varying the inner corediameter and wall thickness. The experimental data are in agreement with numericalmodelling of the optical properties which further reveal highly localized and enhancedelectric fields around the nanotubes. The tunable nature of the optical responseexhibited by such structures could be important for various label-free sensingapplications based on both refractive index sensing and surface-enhanced Ramanscattering.