Boosting Sensing Performance through Near-Field Engineering in Low-Q Metasurfaces

TL;DR

This paper demonstrates that low-Q dielectric metasurfaces, through near-field engineering of evanescent modes, can achieve high sensing sensitivity comparable to high-Q structures, offering a new approach for substance detection.

Contribution

The study introduces a novel mode engineering strategy in low-Q dielectric metasurfaces to enhance sensing performance, challenging the reliance on high-Q resonators.

Findings

Low-Q metasurfaces can surpass traditional sensitivity limits.

Near-field engineering optimizes electromagnetic field overlap with analytes.

Engineered modes enable high detection performance without ultra-high-Q resonances.

Abstract

Dielectric metasurfaces have introduced a new paradigm for substance detection by exploiting their resonant properties to enhance light-matter interaction. This enhancement can be used for sensing either through refractive index changes or through absorption-based mechanisms. Most works focus on high-quality factor resonators, aiming to increase field confinement in the vicinity of the resonant structure to improve sensitivity. In this work, we explore an alternative approach based on low-quality factor, fully dielectric metasurfaces, with engineered modes to enhance near-field concentration. We investigate different topologies that, despite their low-quality factors, achieve sensitivity and detection performance beyond what is typically reported for low-Q structures in the literature. This improvement is enabled by near-field engineering of the evanescent modes, allowing us to control the spatial distribution of the electromagnetic field and maximize its overlap with the analyte. Our results show that careful mode engineering provides a powerful strategy to boost sensing performance without relying on ultra-high-Q resonances.