UCLA

By using finite-difference time-domain simulation, we investigate the enhancement of local electrical field by combining localized surface plasmon (LSP) of Au nanopyramid array and surface plasmon polaritons (SPPs) focused by Au nanorings. We report on the systematic investigation of structural variables that could affect the coupling efficiency between SPPs and LSP to obtain optimal design. The study aims at finding the quasi-quantitative relation between several key-variables of the pyramid-ring combination and the overall surface enhanced Raman spectroscopy (SERS) enhancement at the center of the structure. We consider the following factors that could affect the interaction between SPPs and LSP: ring radius, number of rings, pyramid spacing, number of pyramids, and the relative position of ring center and pyramid array center. By adjusting these structural variables, high electric field enhancement of up to 140× and large volume of hot spots can be achieved. We also investigate the incorporation of the LSP-SPP hybrid structure onto the facet of optical fiber for SERS-based detection.