Either Electric or Magnetic Field Hugely Enhanced by Coupling to Optical Energy Focusing Structure

We introduce a new optical energy focusing structure consisting of a circular dielectric Bragg nanocavity and a circular metallic plasmonic lens. Via the hybridization of Bragg cavity modes and surface plasmon modes, optical... [ view full abstract ]

We introduce a new optical energy focusing structure consisting of a circular dielectric Bragg nanocavity and a circular metallic plasmonic lens. Via the hybridization of Bragg cavity modes and surface plasmon modes, optical energy is highly confined in the central region of the Bragg nanocavity under linearly polarized illumination. When either a Bowtie Nano-antenna (BNA) or a Magnetic Resonator (MR) is placed on this focusing structure, the energy can be high-efficiency coupled and focused into the BNA or MR. Simulations show that the electric field enhancement (|E|/|E0|) in the BNA and magnetic field enhancement (|H|/|H0|) in the MR can be more than 3000 and 200, respectively, which are both currently the highest as far as we know. This proposed hybrid dielectric-metallic structure opens a new avenue in energy focusing and transferring and provides opportunities for various applications, including single-molecule SERS, optical trapping, photolithography, fluorescent microscopy, magnetic sensors, etc.