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Broadband infrared circular dichroism in chiral metasurface absorbers
摘要： Chirality is ubiquitous in nature and it is essential in many fields, but natural materials possess weak and narrow-band chiroptical effects. Here, chiral plasmonic metasurface absorbers are designed and demonstrated to achieve large broadband infrared circular dichroism (CD). The broadband chiral absorber is made of multiple double-rectangle resonators with different sizes, showing strong absorption of left-handed or right-handed circularly polarized (LCP or RCP) light above 0.7 and large CD in absorption more than 0.5 covering the wavelength range from 1.35 μm to 1.85 μm. High broadband polarization-dependent local temperature increase is also obtained. The switchable infrared reflective chiral images are further presented by changing the wavelength and polarization of incident light. The broadband chiral metasurface absorbers promise future applications in many areas such as polarization detection, thermophotovoltaics, and chiral imaging.
关键词： chiral image,broadband,Chiral metasurface,circular dichroism
更新于2025-09-23 15:19:57
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Switching the Optical Chirality in Magnetoplasmonic Metasurfaces Using Applied Magnetic Fields
摘要： Chiral nanophotonic devices are promising candidates for chiral molecule sensing, polarization of diverse nanophotonics, and display technologies. Active chiral nanophotonic devices, where the optical chirality can be controlled by an external stimulus has triggered great research interest. However, efficient modulation of the optical chirality has been challenging. Here, we demonstrate switching of the extrinsic chirality by applied magnetic fields in a magnetoplasmonic metasurface device based on a magneto-optical oxide material, Ce1Y2Fe5O12 (Ce:YIG). Due to the low optical loss and strong magneto-optical effect of Ce:YIG, we experimentally demonstrated giant and continuous far-field circular dichroism (CD) modulation by applied magnetic fields from ?0.6 ± 0.2° to +1.9 ± 0.1° at 950 nm wavelength under glancing incident conditions. The far-field CD modulation is due to both magneto-optical circular dichroism and near-field modulation of the superchiral fields by applied magnetic fields. Finally, we demonstrate magnetic-field-tunable chiral imaging in millimeter-scale magnetoplasmonic metasurfaces fabricated using self-assembly.
关键词： optical chirality,magneto-optical effect,magnetoplasmonic,metasurface,circular dichroism,magnetic oxides
更新于2025-09-23 15:19:57
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Detailed Experiment-Theory Comparison of Mid-Infrared Metasurface Perfect Absorbers
摘要： Realisation of a perfect absorber A = 1 with transmittance and reflectance T = R = 0 by a thin metasurface is one of the hot topics in recent nanophotonics prompted by energy harvesting and sensor applications (A + R + T = 1 is the energy conservation). Here we tested the optical properties of over 400 structures of metal–insulator–metal (MIM) metasurfaces for a range of variation in thickness of insulator, diameter of a disc and intra-disc distance both experimentally and numerically. Conditions of a near perfect absorption A > 95% with simultaneously occurring anti-reflection property (R < 5%) was experimentally determined. Differences between the bulk vs. nano-thin film properties at mid-IR of the used materials can be of interest for plasmonic multi-metal alloys and high entropy metals.
关键词： mid infrared absorption,metasurface,perfect absorption
更新于2025-09-23 15:19:57
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Metamaterials - Devices and Applications || Effects of Dielectric Substrate on Polarization Conversion Using Coupled Metasurfaces With and Without Tunneling
摘要： Dielectric substrates are technologically necessary components of various microwave and optical structures and devices, and may strongly affect their performance. For metasurfaces composed of subwavelength resonators, placing dielectric components in the proximity of resonators can lead to strong modification of subwavelength resonances and related transmission regimes. We focus on the effects exerted by material and geometrical parameters of such a dielectric substrate on linear-to-linear polarization conversion that appears in quasiplanar structures containing two coupled metasurfaces and enabling chirality. It is shown that spectral locations of the polarization conversion resonances and transmission efficiency at these resonances are strongly sensitive to the substrate parameters, whereas the ability of polarization conversion and related asymmetry of transmission can be preserved in wide ranges of parameter variation. The effects of a substrate are considered in detail for the mechanisms with and without tunneling, indicating a route to compact designs of quasiplanar structures for single- and multiband polarization conversion.
关键词： permittivity,subwavelength resonator,polarization conversion,metasurface
更新于2025-09-23 15:19:57
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High-purity orbital angular momentum states from a visible metasurface laser
摘要： Orbital angular momentum (OAM) from lasers holds promise for compact, at-source solutions for applications ranging from imaging to communications. However, conjugate symmetry between circular spin and opposite helicity OAM states (±?) from conventional spin–orbit approaches has meant that complete control of light’s angular momentum from lasers has remained elusive. Here, we report a metasurface-enhanced laser that overcomes this limitation. We demonstrate new high-purity OAM states with quantum numbers reaching ??=?100 and non-symmetric vector vortex beams that lase simultaneously on independent OAM states as much as Δ??=?90 apart, an extreme violation of previous symmetric spin–orbit lasing devices. Our laser conveniently outputs in the visible, producing new OAM states of light as well as all previously reported OAM modes from lasers, offering a compact and power-scalable source that harnesses intracavity structured matter for the creation of arbitrary chiral states of structured light.
关键词： chiral states,metasurface,Orbital angular momentum,visible light,laser
更新于2025-09-23 15:19:57
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Thermally tunable terahertz metasurface absorber based on all dielectric indium antimonide resonator structure
摘要： In this paper, we present a novel design of temperature tunable metasurface absorber (MSA) based on all dielectric indium antimonide (InSb) resonator structure in terahertz (THz) region. The permittivity of the InSb dielectric is dependent on the variation of temperature. Based on the perfect impedance-match (Re(z)?1) to the free space, the absorbance of the proposed MSA is up to 99.9% at 1.43 THz and the Q-factor is about 26.9 when temperature is 285 K. The perfect absorption of the MSA is mainly from excitation of fundamental dipolar mode. In addition, the MSA is polarization-insensitive for both transverse electric (TE) and transverse magnetic (TM) waves. Furthermore, the absorption properties of the MSA can be adjusted by changing the geometric parameters of the unit-cell structure and temperature. The design offers a new route for control of THz absorption with potential applications in imaging, energy harvesting, sensing, and detecting.
关键词： Terahertz,Tunable,Metasurface absorber,Indium antimonide (InSb)
更新于2025-09-23 15:19:57
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Color filtering and displaying based on hole array
摘要： Metastructure color displays based on the rectangular hole arrays are proposed. The transmission spectrum of hole array etched on the silver film depends on the length and width of rectangular hole, the period of hole array and the polarization direction of illuminating light. Three primary colors with high purity are obtained through adjusting the parameters of hole array, and the color displaying is realized by using the polarization dependence of the transmission spectrum. Two color displays consisting of three suits of hole arrays are provided and the detected transmission intensity verify their performance in color displaying. The proposed metasurface color displays can be used to separate colors with high fidelity and analyzes the incident polarization, and their ultrathin and compact structures are benefit to expanding its applications in color information processing.
关键词： Nanohole,Color filtering,Metasurface,Polarization
更新于2025-09-23 15:19:57
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Transparent Metasurfaces Counteracting Fogging by Harnessing Sunlight
摘要： Surface fogging is a common phenomenon that can have significant and detrimental effects on surface transparency and visibility. It affects the performance in a wide range of applications including windows, windshields, electronic displays, cameras, mirrors, and eyewear. A host of ongoing research is aimed at combating this problem by understanding and developing stable and effective anti-fogging coatings that are capable of handling a wide range of environmental challenges 'passively' without consumption of electrical energy. Here we introduce an alternative approach employing sunlight to go beyond state-of-the-art techniques—such as superhydrophilic and superhydrophobic coatings— by rationally engineering solar absorbing metasurfaces that maintain transparency, while upon illumination, induce localized heating to significantly delay the onset of surface fogging or decrease defogging time. For the same environmental conditions, we demonstrate that our metasurfaces are able to reduce defogging time by up to four-fold and under supersaturated conditions inhibit the nucleation of condensate outperforming conventional state-of-the-art approaches in terms of visibility retention. Our research illustrates a durable and environmentally sustainable approach to passive anti-fogging and defogging for transparent surfaces. This work opens up the opportunity for large-scale manufacturing that can be applied to a range of materials, including polymers and other flexible substrates.
关键词： renewable energy,condensation,defogging,anti-fogging,metasurface
更新于2025-09-19 17:15:36
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High-Gain Circularly Polarized Fabry–Pérot Patch Array Antenna with Wideband Low-Radar-Cross-Section Property
摘要： In this paper, we explore the adoption of a chessboard polarization conversion metasurface (CPCM) for constructing a low-radar-cross-section (RCS), high-gain circularly polarized (CP) patch array antenna. The proposed CPCM is used as the polarization conversion metasurfaces’ chessboard configuration, which consists of adjacent two-layer substrates that have three metallic models. Low RCS is achieved by 180° (±30°) reflection phase variations of two adjoining PCMSs. Gain enhancement is achieved by adopting a Fabry–Pérot cavity constituted by a PCM and the antenna’s ground. The antenna with a CPCM that operates at X/Ku band, excited by the feeding network that is rotated sequentially, is measured and fabricated. The patch array antenna impedance bandwidth based on PCM was measured as 3.3 GHz (9.5–12.8 GHz) with a 3-dB axial ratio bandwidth of 11.6% and a high gain of 13.4 dBiC (9.5–12 GHz), more than 2.5 dB higher compared with a patch antenna without a PCM. In addition, the patch array antenna produced a useful wideband RCS decrease in the operational bandwidth from 9 to 13 GHz.
关键词： low radar cross-section,dual patch,polarization conversion metasurface,circularly polarized
更新于2025-09-19 17:15:36
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Controlling the Near-Field of Metasurfaces for Free-Electron Multi-Harmonic Hard X-Ray Generation
摘要： Metasurfaces are subwavelength spatial variations in geometry and material, and offer us an ingenious way of manipulating far-field radiation. Here, we show that their ability to manipulate the near-field is also an extremely powerful lever in controlling nanophotonic photon-electron interactions. The metasurface near-field contains high-order spatial harmonics that can be leveraged to generate substantial high harmonic components, whose properties are directly tunable through the metasurface geometry, the electron energy and the incidence angle of the input laser. By developing an analytical theory that produces results in excellent agreement with our ab initio simulations, we show how the design of metasurface-enhanced plasmons can be leveraged to produce intense and highly-directional multi-harmonic emission in the X-ray and the gamma-ray range. Furthermore, we show that the use of few-cycle laser pulses is instrumental in enhancing the intensity and bandwidth of the radiation output while avoiding damage to the metasurface. As an example, we present the design of a four-color X-ray source.
关键词： X-rays,sources,ultrafast optics,plasmonics,metasurface
更新于2025-09-19 17:15:36