2020 Volume 12 Issue 1 Pages 21-27
In this research, we simulated the plasmonic properties of a single metal nanodisk excited by an optical vortex beam (OVB) using the discrete dipole approximation (DDA) method. The properties of the extinction spectra are related to the diameter and thickness of the gold nanodisk, and these spectra showed a sharper peak at shorter wavelength ranges compared to using linear polarized Gaussian beams. The peak wavelength shifts depending on the structural parameter when excited by a Gaussian beam. However, in the case of OVB use, there is minimal change observed in the peak wavelength. This tendency indicates that the localized plasmon resonance (LPR) properties excited by an OVB are dominated by the state of the excitation beam and not the shape and size of nanostructures. Focusing on distributions of photoelectric fields at peak wavelengths, the excited hexapole type mode showed behaviors of the resonance while rotating over time. This phenomenon is not seen in general excitation. These plasmonic properties reflect the temporal and spatial phase change of incident OVBs are of great interest. These results indicate that LPR properties can be designed by tuning not only the material, shape, and size, but also the condition of light excitation.
