Size dependence of simulated optical properties for Cu nanocubes

Abstract

This paper reports a systematic investigation on the optical properties of Cu nanocubes as a function of the edge length by the discrete dipole approximation. In the far-field, our results showed that the extinction resonance peak shifted to long wavelength from 595 nm to 670 nm as the size increased from 10 nm to 90 nm. Also, the highest optical efficiencies for absorption and scattering were obtained for the nanocubes that were 50 nm and 90 nm in size, respectively. In the near field, the effects of the edge length on the local electric field were investigated considering the extinction spectra peak as the excitation wavelength. The near field intensity increased with size from 10 nm to 60 nm, being the highest at the excitation wavelength of 630 nm in edge length of 60 nm, followed by a decrease at larger sizes. The size dependence of far-field and near-field optical properties described here can guide design of plasmonic nanostructures for applications in nonlinear spectroscopy, near-field lithography and plasmonic solar cells.