Plasmonic optical antennas on dielectric gratings with high field enhancement for surface enhanced Raman spectroscopy

We present a rational approach toward amplifying the local electromagnetic (EM) field for surface enhanced Raman spectroscopy applications by integrating dielectric gratings capable of guided mode resonance with plasmonic optical antennas. The optical antennas are placed periodically at certain positions on the surface of a two-dimensional (2D) dielectric grating. At resonance, the grating provides a spatially confined, enhanced EM field that can further enhance the strong field of the localized surface plasmon on the nanoantenna. The numerical simulations demonstrate a cascaded enhancement from the optical antenna and the dielectric grating when the two are weakly coupled.