Huge local electric field enhancement in hybrid plasmonic arrays

In this Letter, a novel hybrid nanoparticle array with huge local electric field intensity enhancement is proposed theoretically. The hybrid array is constructed by replacing some nanodisks with nanobowties from a perfect nanodisk square array. In our structure, the nanodisk array, which acts as a two-dimensional grating, can efficiently excite surface plasmon polaritons (SPPs) modes, whose electric field is much larger than the incident light. Then the SPPs mode excites the localized surface plasmon resonance (LSPR) mode of the nanobowties. When the resonant peaks of the array and the nanobowties coincide, the nanobowties are strongly excited, and the maximum intensity enhancement factor (E/E0)2 as large as 4.2×10(6) is achieved. A two-step excitation model is proposed to help us to understand the underlying physical mechanism for this enhancement. This hybrid array structure shows great potential in highly sensitive surface enhanced Raman scattering and fluorescence detection.