Polarization Anisotropy of Multiple Localized Plasmon Resonance Modes in Noble Metal Nanocrescents

Multiple localized surface plasmon resonance (LSPR) modes induced in gold and silver nanocrescents exhibit anisotropic behavior with respect to polarization of incident light. Extinction spectroscopy with polarization control was used to characterize the optical properties of asymmetric nanocrescents with diameters ranging from 100 to 500 nm. The analysis shows that selective induction of distinct dipole and quadrupole LSPR modes can be accomplished through polarization of incident light. Finite-difference time-domain calculations of the LSPR responses of the nanocrescent corroborate the polarization-dependent optical behavior. Simulations reveal optical near field enhancements with unique spatial patterns associated with the individual resonance modes depending on the polarization and wavelength of incident light. Quantitative analysis of the anisotropic LSPR behavior supports the potential for controlling the near field through selective induction of specific resonance modes with particular near field distributions.