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Ultraviolet (UV, 200-400 nm) detection with high efficiency and excellent spectral resolution is essential in spectral analysis. This Letter proposes a UV narrowband all-dielectric metasurface absorber with an ultra-thin absorption layer. The design incorporates lossless AlO resonators placed on a thin (20 nm) lossy GaO film, which enhances the absorption intensity at a specific wavelength. The near-perfect narrowband absorption enhancement results from the spectral overlap of the magnetic dipole (MD) and the electric dipole (ED) absorption modes by surface lattice resonance (SLR). The proposed absorber exhibits high-efficiency and high-quality (Q) absorption performance (A > 95%, Q ∼ 231) and allows for flexible control over the absorption wavelength through simple parameter adjustments. These features make it ideal for narrowband emission, spectrum detection, and multispectral sensing.
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http://dx.doi.org/10.1364/OL.554792 | DOI Listing |
Currently, it remains a challenge for micro-transmission filters based on diffractive nanostructures to achieve a balance among the spectral range, transmission efficiency, and color purity. While plasmonic metal metasurfaces of Fabry-Pérot (FP) cavities offer a wide spectral range, they are hindered by large full width at half maximum (FWHM) and low transmission efficiency; on the other hand, all-dielectric FP cavities exhibit small FWHM and high transmission efficiency but narrow spectral range. This study presents an innovative second-order FP cavity structure, wherein the introduction of a metal layer modifies the electromagnetic field distribution inside the cavity, leading to a shift in resonance modes.
View Article and Find Full Text PDFNanomaterials (Basel)
July 2025
College of Advanced Interdisciplinary Studies & Hunan Provincial Key Laboratory of Novel-Optoelectronic Information Materials and Devices, National University of Defense Technology, Changsha 410073, China.
Enhancing light absorption in two-dimensional (2D) materials, particularly few-layer structures, is critical for advancing optoelectronic devices such as light sources, photodetectors, and sensors. However, conventional absorption enhancement strategies often suffer from unstable resonant wavelengths and low-quality factors (Q-factors) due to the inherent weak light-matter interactions in 2D materials. To address these limitations, we propose an all-dielectric metasurface graphene-perfect absorber based on toroidal dipole bound state in the continuum (TD-BIC) with an ultra-narrow bandwidth and stable resonant wavelength.
View Article and Find Full Text PDFThe design of infrared circularly polarized emission sources has garnered significant interest in fields such as vibrational circular dichroism (CD) spectroscopy. This study proposes a planar chiral all-dielectric metasurface based on quasiguided modes to achieve narrowband, high CD chiral thermal emission sources in the mid-infrared (MIR) region. To address the fabrication challenges associated with traditional three-dimensional chiral structures, this design introduces in-plane displacement perturbations, achieving chiral thermal emission through Brillouin zone folding and the breaking of mirror symmetries.
View Article and Find Full Text PDFNanoscale Horiz
May 2025
Sichuan University, Chengdu, 610207, China.
One typical characteristic of conventional all-dielectric terahertz metamaterials is their thickness, which is designed to be dozens of, or even one hundred microns, to reduce the leakage of the resonant field to the substrate. In the frequency range of 2 THz to 3 THz, we propose a substrate-free ultra-thin all-dielectric terahertz metamaterial (UATM) composed of a silicon (Si) dual-ellipse array and silicon dioxide (SiO) supporting layer with thicknesses of 5 μm and 2 μm, respectively. The UATM exhibits quasi-bound state in the continuum (quasi-BIC) modes related to the tilt angle and period parameters.
View Article and Find Full Text PDFiScience
April 2025
Key Laboratory of Atomic and Subatomic Structure and Quantum Control (Ministry of Education), Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, School of Physics, South China Normal University, Guangzhou 510006, China.
Local metasurfaces provide high flexibility in shaping wavefronts but suffer from poor frequency selectivity. Here, we numerically present a reflective all-dielectric metasurface platform achieving simultaneous local phase control and spectral filtering: it reshapes the wavefront at a specific wavelength while spatially separating it from other wavelengths without requiring additional optics. The highly efficient phase control is inherently linked to the high polarization conversion ratio (PCR), ensured by a silicon nanoblock as a narrowband reflective half-wave plate through fundamental Mie resonances.
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