Asymmetric L-shaped resonant optical antennas with plasmon length tuning and high-electric field enhancement

Abstract L-shaped resonant optical antennas (ROAs) are low-symmetry plasmonic nanostructures with the unique ability to show two tunable resonances in and near-infrared wavelength regions. The plasmon length of so-called longitudinal dipolar fundamental mode these asymmetric ROAs can be used as resonance building blocks design polarization-sensitive devices. This paper introduces numerically analyzes a novel L-shape ROAs. reported offers modes, i.e., bimodal antenna behavior high enhancement factor. These selectively excited by changing linear polarization angle. It is found that coupled ROA very small 2 nm gap width exhibits field enhancements 40 147.3 on scale $$\left|{E}_{TOT}\right|/\left|{E}_{IN}\right|$$ E TOT / IN for energy low resonance, respectively. obtained results analysis open new route multiple devices ultra-high easily integrated future nano-optical circuits operational frequencies.