Hybridization-induced resonances with high quality factor in a plasmonic concentric ring-disk nanocavity

TL;DR

This paper proposes a novel plasmonic nanocavity design that achieves ultra-high Q factors and narrow resonance linewidths through hybridization effects, enabling advanced on-chip sensing and photonic applications.

Contribution

It introduces a new concentric ring-disk plasmonic resonator with hybridization-induced high Q factors and ultra-narrow linewidths, surpassing traditional limitations of plasmonic resonators.

Findings

Q factor exceeds 400

FWHM nearly 1 nm

Enhanced refractive index sensing performance

Abstract

Plasmonic resonators have drawn more attention due to the ability to confine light into subwavelength scale. However, they always suffer from a low quality (Q) factor owing to the intrinsic loss of metal. Here, we numerically propose a plasmonic resonator with ultra-high Q factor based on plasmonic metal-insulator-metal (MIM) waveguide structures. The resonator consists of a disk cavity surrounded by a concentric ring cavity, possessing an ultra-small volume. Arising from the plasmon hybridization between plasmon modes in the disk and ring cavity, the induced bonding hybridized modes have ultra-narrow full wave at half maximum (FWHM) as well as ultra-high Q factors. The FWHM can be nearly 1 nm and Q factor can be more than 400. Furthermore, such device can act as a refractive index sensor with ultra-high figure of merit (FOM). This work provides a novel approach to design plasmonic high-Q-factor resonators, and has potential on-chip applications such as filters, sensors and nanolasers.