Study of multipole excitation of plasmon resonance in metal nanostructure using optical vortices

Tóm tắt

Since 19th century, nanomaterial has been considered a promising material that
 can create a big jump in technology due to its special properties. The reason for the
 difference is based on the size effect of the material. With nanoscale size, the number
 of surface atoms increases significantly and takes a pivotal role in forming the material
 properties. Hence, the surface plasmon resonance effect becomes sig- nificantly strong
 in the nanomaterial. The plasmon effect was observed in the early 20th century by Prof
 Robert W. Wood and under research the following time. Up to now, Surface Plasmon
 Resonance (SPR) has been applied in many fields such as bio-detection, solar cells, and
 surface-enhanced Raman scattering. However, in the late 20th century Optical Vortices
 (OVs) was discovered as a new type of light with a topological charge and singularity
 in the optical axis. This light creates a new plasmon effect known as the Multipole
 Plasmon Resonance (MPR). In this thesis, I investigate the formation of the multipole
 plasmon resonance effect on metal nanostructures with different shapes and sizes. I use
 the DDSCAT program to simulate the interaction of a Laguerre-Gaussian beam (one
 mode of optical vor- tex) with the sample. Then, by analyzing the absorption and
 scattering spectrum we come up with the dependence of the MPR wavelength on the
 shape and size of the sample. By looking at the near-field electric distribution of the
 sample we can conclude the connection between the MPR state with the topological
 charge. Overall, my thesis provides a basic phenomenon about the MPR effect which
 is created by a Laguerre-Gaussian beam. This result can be used as reference information for future research in optical manipulation, optical communication, and
 optical properties of material.