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Ultracompact and dynamically tunable plasmonic THz switch based on graphene microcavity metamaterial
摘要： We propose and discuss a compact and tunable plasmonic terahertz (THz) metamaterial switch based on graphene micro-cavity. Due to the joint effect of graphene plasmon resonances and Fabry–Perot oscillations, this metamaterial structure can be switched from the ON state to OFF state with the maximum intensity attenuation larger than 95% (ON–OFF ratio larger than 30 dB). The central frequency of the switch could be tuned in a wide frequency range from 3.6 to 9.6 THz by tuning the Fermi energies of the graphene patterns. Moreover, the metamaterial structure is valid for a wide range of incident angles of both transverse electric (TE) and transverse magnetic (TM) polarizations with the highest Q factor of 15.5. This investigation promises the development of high-performance, widely tunable THz switch in chip integrated photonic circuits without reconstructing the physical structures.
关键词： Terahertz,Switch,Graphene,Metasurface
更新于2025-09-23 15:21:01
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Coupled Mode Demonstration of Slow-Light Plasmonic Sensor Based on Metasurface at Near-Infrared Region
摘要： In this paper, we theoretically and numerically reported a dual plasmon-induced transparency and the relevant sensing property in a multi-cross metasurface by the coupled mode analysis. A phase coupling model was established to characterize the optical response of this plasmonic sensor. It was found that the transparency windows were sensitive to the resonance mode of each metal strip, which was well demonstrated by the theoretical model. Both the sensing property and the slow light in this structure were discussed. A high figure of merit of 223 and sensitivity of 850 nm/RIU were achieved. In addition, the 1170-nm near-infrared light can be slowed down by nearly two order of magnitude with group delay of 0.45 ps in this sensor. These results may provide guidance for light-matter interaction-enhanced slow-light sensor and integrated optical circuit design.
关键词： Plasmon-induced transparency,Plasmonic sensor,Metasurface,Slow light,Coupled mode theory
更新于2025-09-23 15:21:01
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A metasurfacea??enabled wideband higha??gain duala??circularlya??polarized Fabrya??Perot resonator antenna
摘要： This paper presents a wideband high-gain dual-circularly-polarized (CP) antenna with a simple configuration. Instead of improving the gain using the dual-CP element array, the Fabry-Perot resonator antenna concept is applied in this work. By designing a dual-linearly-polarized Fabry-Perot resonator antenna and a linear-to-circular polarization (LP-CP) metasurface polarizer separately and combining them, a wideband high-gain dual-CP antenna can be achieved. Structural simplicity and less design difficulty are advantages of the antenna design. Experimental results validate the design concept. It exhibits 3-dB axial-ratio bandwidths of over 12% for both LHCP and RHCP performance, a high polarization isolation of over 25 dB, and peak gains of 12.78 dBi and 12.89 dBi for LHCP and RHCP radiations respectively.
关键词： wideband,metasurface,dual-circularly-polarized,high-gain,Fabry-Perot resonator antennas
更新于2025-09-23 15:21:01
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Temperature Tunable Narrow-Band Terahertz Metasurface Absorber Based on InSb Micro-Cylinder Arrays for Enhanced Sensing Application
摘要： A narrow-band metasurface absorber (MSA) based on InSb micro-cylinder arrays has been proposed and investigated numerically, which could be believed to be applicable for both temperature and refractive index (RI) sensing in terahertz (THz) region. Distinct from previous designs, the proposed narrow-band MSA is only consisted of a sub-wavelength periodic micro-cylinder array based on the InSb material possessing an extremely thermosensitive relative permittivity which varies with the external environment temperature, and a gold ground-plane deposited on a glass substrate. Numerical simulation results indicate that the proposed MSA can achieve an absorbance of 99.9% at 1.8985 THz and the corresponding Q-factor is about 120.9 at room temperature (300 K). It is inferred that the narrow-band perfect absorption of the MSA could be contributed to the surface plasmon polariton (SPP) resonance mode excitation. Furthermore, the absorption property of the designed MSA is found to be highly sensitive to the RI value variations of the surrounding mediums and fluctuations of external environment temperature. Thus, the proposed MSA can be not only operated as a temperature sensor with a sensitivity of 2.13 GHz/K, but also a RI sensor with a sensitivity of 960 GHz/RIU (refractive index unit). Due to its high sensing performance, it can be believed that the narrow-band MSA has great potential applications in chemical, biological or other optoelectronic related areas.
关键词： terahertz region,Metasurface absorber,sensing,InSb,narrow-band
更新于2025-09-23 15:21:01
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Infrared spectroscopy of live cells from a flowing solution using electrically-biased plasmonic metasurfaces
摘要： Spectral cytopathology (SCP) is a promising label-free technique for diagnosing diseases and monitoring therapeutic outcomes using FTIR spectroscopy. In most cases, cells must be immobilized on a substrate prior to spectroscopic interrogation. This creates significant limitations for high throughput phenotypic whole-cell analysis, especially for the non-adherent cells. Here we demonstrate how metasurface-enhanced infrared reflection spectroscopy (MEIRS) can be applied to a continuous flow of live cell solution by applying AC voltage to metallic metasurfaces. By integrating metasurfaces with microfluidic delivery channels and attracting the cells to the metasurface via dielectrophoretic (DEP) force, we collect the infrared spectra of cells in real time within a minute, and correlate the spectra with simultaneously acquired images of the attracted cells. The resulting DEP-MEIRS technique paves the way for rapid SCP of complex cell-containing body fluids with low cell concentrations, and for the development of a wide range of label-free liquid biopsies.
关键词： dielectrophoretic force,live cells,FTIR spectroscopy,microfluidic delivery channels,Spectral cytopathology,metasurface-enhanced infrared reflection spectroscopy,label-free liquid biopsies
更新于2025-09-23 15:21:01
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High-sensitivity biosensor for identification of protein based on terahertz Fano resonance metasurfaces
摘要： Terahertz metasurface biosensors have gained significant attention in biological field due to its label-free, real-time and in-situ detection properties. In this paper, a planar array of Fano asymmetric split ring resonators (ASRs) fabricated on 25 μm flexible polyimide substrate was proposed for new terahertz metasurface biosensors. It is shown that 160 GHz/RIU and 240 GHz/RIU refractive index sensitivity can be severally obtained near 0.81 and 1.13 THz transmission dips of the proposed system. Correspondingly, for biosensor samples that protein A/G, A/G + IgG were spotted on ASRs surface in our experiment, shifts of 8.9 GHz and 11.7 GHz, 17.6 GHz and 52.9 GHz toward low frequency were observed, respectively. These results illustrate high-sensitivity and label-free detection of proteins, implying a new feasible way of sensing in terahertz domain.
关键词： Fano resonance,Terahertz,Biosensor,Metasurface
更新于2025-09-23 15:21:01
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Near-field observation of guided-mode resonances on a metasurface via dielectric nanosphere excitation
摘要： We study laser-induced guided-mode resonances on an ultra-thin anisotropic metallic metasurface using direct near-field mapping. Coupling of the incident light to the surface waves is provided by a resonant laser-printed silicon nanosphere placed on the metasurface using nano-manipulation under electron-beam supervision. To visualize the propagation of the guided modes, we employ scattering-type scanning near-field optical microscopy in the near-infrared region (850 nm). The guided-mode resonances excited by the nanosphere demonstrate vanishing anisotropy due to weak confinement at the metasurface/air interface. We also extract the wavenumber of the observed modes through Fourier transformation of the measured near-field maps and find it to be in good agreement with numerical calculations.
关键词： Metasurface,Surface waves,Anisotropy,s-SNOM,Guided-mode resonance,Nano-Optics
更新于2025-09-23 15:21:01
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Feasibility Analysis of Nanostructured Planar Focusing Collectors for Concentrating Solar Power Applications
摘要： Concentrating solar power (CSP) technology is an attractive approach to harvesting solar energy. Unlike photovoltaic (PV) technology, thermal storage is used in lieu of batteries for electricity generation. However, the cost of current collection optics in a CSP plant hampers commercial competitiveness with PVs and natural gas. The use of a planar focusing collector (PFC) could help reduce cost of materials, installation, and maintenance. We present two candidate PFC designs, one based on metasurfaces and the other a Fresnel-like model. We feed each design through the entire system process—design, fabrication, scalability, and techno-economic feasibility—and discuss the challenges met at each stage. Two-photon and nanoimprint lithography are used to make PFC molds and replicas, respectively. We find that the annual optical efficiency for the Fresnel-based PFC is ~40%--higher than the current 30% target for natural gas, thereby suggesting potential economic advantages in the market of industrial process heat.
关键词： Metasurface,Two-Photon Lithography,Concentrating Solar Power (CSP),Planar Focusing Collector (PFC),Nanoimprint Lithography
更新于2025-09-23 15:21:01
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Low-profile wideband circularly polarised single-layer metasurface antenna
摘要： A novel low-pro?le single-fed circularly polarised single-layer metasurface antenna for wideband operation is proposed in this Letter. The metasurface antenna consists of nine unit cells arranged in a 3 × 3 layout. Four slits are incorporated into four of them, respectively, to form two orthogonal currents with 90° phase difference; hence, circularly polarised ?elds are excited. Moreover, a modi?ed L-type slot is etched on the middle lattice to improve impedance bandwidth and axial ratio performance. The proposed dielectric-?lled (?r = 3.5, tan δ = 0.001) antenna with a low pro?le of 0.038λ0 (λ0 is the working wavelength at 5.7 GHz in free space) achieves about 18.0% measured ?10 dB impedance bandwidth. The measured 3-dB axial ratio bandwidth of the proposed antenna is about 12.8% (5.35–6.08 GHz) with a broadside gain of more than 6.9 dBi.
关键词： low-profile,metasurface antenna,wideband,circularly polarised,single-layer
更新于2025-09-23 15:21:01
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Metasurfaces for Terahertz Wavefront Modulation: a Review
摘要： Metasurface is an artificial material composed of a series of subwavelength structure units and has unique electromagnetic characteristics. Based on the ability of manipulating the phase, amplitude, and polarization of electromagnetic wave, various kinds of metasurfaces are designed to realize wavefront manipulations, such as beam focusing, beam steering, vector beams generating, and holographic imaging. This paper reviews the design methods of metasurfaces for wavefront modulation and evolution of the metasurfaces designed for wavefront manipulation in the terahertz (THz) region. The metasurfaces can be divided into two categories: passive and active metasurfaces. For the passive metasurfaces, the single-functional metasurfaces, multifunctional metasurfaces, and high diffraction efficient metasurfaces designed for various THz wavefront shaping, such as focusing, imaging, and special beams generating, are reviewed. For the active metasurfaces, the metasurfaces with fixed structure and all-optical metasurfaces without fixed structure for THz wavefront modulation are summarized. Furthermore, a comparison on the performance of different kinds of metasurfaces for THz wavefront modulation is presented and the development direction and challenges of the THz wavefront modulation metasurfaces in the future are discussed.
关键词： Active metasurface,Wavefront modulation,Terahertz,Passive metasurface
更新于2025-09-23 15:19:57