Numerical studies on absorption characteristics of plasmonic metamaterials with an array of nanoshells

A numerical study was carried out for absorptance of light with wavelength in the range of 400–900 nm at normal incidence on a 3-layer plasmonic metamaterial, consisting of an array of Au nanoshell structures on the top and a Au layer at the bottom with a Al2O3 layer in between. The Finite-difference time-domain method with appropriate dielectric functions is used to obtain numerical results for the absorptance of light in the plasmonic metamaterial. It was found that the geometric configuration of the nanoshell could change the wavelength of the surface plasmon resonance without lowering the absorptance. The core material in the nanoshell has little effect on absorptance or on the resonance wavelength. The distance between nanoshells affects absorptance greatly but affects plasmon resonance wavelength only slightly.