# Multi-resonant high-Q plasmonic metasurfaces

## TL;DR

This paper introduces a multi-resonant plasmonic metasurface with high-Q resonances, enabling advanced optical filtering and sensing applications by extending surface lattice resonance techniques.

## Contribution

It demonstrates a novel design of multi-resonant metasurfaces with high quality factors, surpassing previous limitations of plasmonic nanoparticle resonances.

## Key findings

- Resonances with Q ~ 40 achieved
- Multiple narrow resonances demonstrated
- Enhanced control over transmission spectrum

## Abstract

Resonant metasurfaces are devices composed of nanostructured sub-wavelength scatterers that generate narrow optical resonances, enabling applications in filtering, nonlinear optics, and molecular fingerprinting. It is highly desirable for these applications to incorporate such devices with multiple, high-quality-factor resonances; however, it can be challenging to obtain more than a pair of narrow resonances in a single plasmonic surface. Here, we demonstrate a multi-resonant metasurface that operates by extending the functionality of surface lattice resonances, which are the collective responses of arrays of metallic nanoparticles. This device features a series of resonances with high quality factors (Q ~ 40), an order of magnitude larger than what is typically achievable with plasmonic nanoparticles, as well as a narrow free spectral range. This design methodology can be used to better tailor the transmission spectrum of resonant metasurfaces and represents an important step towards the miniaturization of optical devices.