Theoretical Analysis of Hybrid Metal-Dielectric Nanoantennas with Plasmonic Fano Resonance for Optical Sensing

A nanoantenna with Fano response is designed with plasmonic oligomers as a refractive index sensor to enhance surface-enhanced Raman scattering (SERS) in the visible light spectrum. The scattered radiation and field-enhanced interactions of the outer gallium phosphide (GaP) nanoring assembled with an inner heptamer of silver with Fano response are investigated systematically using the finite element method. The characteristics of Fano resonance are found to depend on the size, shape and nature of the materials in the hybrid nanoantenna. The confined electromagnetic field produces a single-point electromagnetic hotspot with up to 159.59 V/m. The sensitivity obtained from the wavelength shift and variation in the scattering cross-section (SCS) shows a maximum value of 550 nm/RIU. The results validate the design concept and demonstrate near-field enhancement, enabling the design of high-performance nanoantennas with enhanced optical sensing and SERS properties.

Automated summary

In this study, a nanoantenna with Fano response was designed as a refractive index sensor to enhance surface-enhanced Raman scattering (SERS) in the visible light spectrum. The investigation of the scattered radiation and field-enhanced interactions revealed the dependence of Fano resonance on the size, shape, and nature of the materials in the hybrid nanoantenna. The results confirmed the design concept and demonstrated the near-field enhancement, showing potential for high-performance nanoantennas with enhanced optical sensing and SERS properties.