Strong-Field-Enhanced Spectroscopy in Silicon Nanoparticle Electric and Magnetic Dipole Resonance near a Metal Surface

Strong-field-enhanced spectroscopy in a hybrid dipole resonance system composed of a low-loss semiconductor nanoparticle and metal film is proposed and demonstrated. This hybrid Si nanoparticle on silver system is featuring extraordinary near-field enhancement and large field confinement. Extensive numerical calculations are carried out to investigate the influence of the gap size, particle diameter, and metal substrate on the near-field enhancement response in the Si particle–metal gap in order to properly model their hybridization. Our analysis reveals that this near-field enhancement originates from the strong gap magnetic resonance response by the Si nanoparticle dipole interaction with metal mirror image and metal film surface plasmon effects. We further demonstrate the strong enhanced Raman spectroscopy of a single silicon nanoparticle over Ag film with a precisely sized molecular spacer layer between them. These results illustrate the capacity and tunability of the low-loss silicon particle on the ...