Localized surface plasmons, surface plasmon polaritons, and their coupling in 2D metallic array for SERS.

A substrate with ease for fabrication is proposed for surface enhanced Raman spectroscopy (SERS). A two-dimensional dielectric grating covered by a thin silver film enables the excitation of both localized surface plasmons (LSPs) and surface plasmon polaritons (SPPs). The finite-difference time-domain simulation results show that the coupling between LSPs and SPPs is able to highly improve the Raman enhancement (2 x 10(9) as obtained by simulation). In addition, the near-field distribution at the top of cubic bumps along the transverse plane presents a highly regular hotspots pattern, which is required for an ideal SERS substrate.