Strong Light Confinement by a Plasmon-Coupled Parabolic Nanoresonator Array

To achieve artificial photosynthesis using sunlight, the photon-flux density problem must be solved. Here, we designed a parabolic resonator array composed of a curved Ag mirror filled with nickel oxide (NiO) as a dielectric material with p-type semiconductor properties. Then, several types of parabolic resonator arrays were combined with Au nanodiscs (Au-ND/parabolic resonator array) to realize modal coupling. The far-field and near-field properties of the parabolic resonator array and Au-ND/parabolic resonator array were investigated by numerical simulation using the finite-difference time-domain method. The parabolic resonator array harvested light in the near field based on constructive interference. The coupling system between the parabolic resonator array and plasmon modes showed significantly large near-field enhancement of more than 100 |E/E0|, which describes the ratio between the induced near-field E and the incident light field E0, and high Q-factor, which is the ratio of the resonance frequency and the full width at half-maximum bandwidth of the resonance. It also exhibited robustness for incident light angle fluctuation. This device further achieves the benefits of conventional modal coupling such as absorption enhancement and coherence interaction between plasmonic particles through the resonator.