Gradient High‐Q Dielectric Metasurfaces for Broadband Sensing and Control of Vibrational Light‐Matter Coupling

Abstract

Surface‐enhanced infrared absorption spectroscopy (SEIRA) emerged as a powerful label‐free technique for highly sensitive and chemical specific analysis. SEIRA can be realized by employing the nanophotonic planar structures such as metasurfaces that can enhance light‐matter interaction in the spectral bands of molecular vibrations. Increasing sample complexity emphasizes the need for more elaborated metasurfaces that can operate simultaneously at different spectral bands, both accessing rich spectral information over a broad IR band as well as resolving subtle differences in the absorption fingerprints through narrow‐band resonances. Here, we introduce a novel concept of all‐dielectric gradient resonant metasurfaces, where the required spectral selectivity is achieved via local high‐Q resonances, while the continuous coverage of a broad spectral range is enabled by the gradual adjustment of the unit‐cell dimensions along the planar structure. The highly tailorable design of the gradient metasurfaces provides unprecedented flexibility for shaping the spectral sampling density to match efficiently the relevant bands of target analytes while keeping a compact device footprint. The versatility of gradient metasurfaces is further demonstrated through the efficiency of both sensing scenarios – including polymer mixture deconvolution and highly sensitive detection of a multistep bioassay involving proteins and lipids – and identification of the onset of vibrational strong coupling regime. The proposed gradient‐resonance platform makes an important contribution to the rapidly evolving and expanding landscape of nonlocal metasurfaces, enabling a broad range of applications in molecular detection and analysis of fundamental light‐matter interaction phenomena.This article is protected by copyright. All rights reserved

Advanced manufacturing of dielectric meta-devices

“…Through specific design and artificial arrangement, metasurfaces demonstrate a remarkable ability to manipulate the wavelength, amplitude, phase, and polarization of electromagnetic waves. This versatility finds applications in diverse fields such as metalenses [11][12][13][14][15][16][17][18][19][20] , metaholograms [21][22][23][24][25][26] , structural colors [27][28][29][30][31][32][33][34] , optical vortex generation [35][36][37][38][39][40] , spectrometers [41][42][43][44] , imaging [44][45][46][47] , sensing [48][49][50][51][52][53][54][55] , and beam manipulation [56][57]…”

Topology Optimization Enables High-Q Metasurface for Color Selectivity

“…Due to the confinement of optical interactions within deeply subwavelength structures, they tend to exhibit broad-band characteristics, resulting in wavefront deformation across a wide frequency range. In contrast, nonlocal metasurfaces, such as guided-mode resonance gratings (RWGs), − quasi-bound states in the continuum (q-BIC) structures, − and perturbative structures, , yield sharp spectral features. This is because guided-mode resonance gratings approximate the pure slab waveguide, enabling the excitation of multiple modes simultaneously at different wavelengths and resulting in higher quality factors ( Q -factor).…”