- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Independent control of harmonic amplitudes and phases via a time-domain digital coding metasurface
摘要： Harmonic manipulations are important for applications such as wireless communications, radar detection and biological monitoring. A general approach to tailor the harmonics involves the use of additional amplifiers and phase shifters for the precise control of harmonic amplitudes and phases after the mixing process; however, this approach leads to issues of high cost and system integration. Metasurfaces composed of a periodic array of subwavelength resonators provide additional degrees of freedom to realize customized responses to incident light and highlight the possibility for nonlinear control by taking advantage of time-domain properties. Here, we designed and experimentally characterized a reflective time-domain digital coding metasurface, with independent control of the harmonic amplitude and phase. As the reflection coefficient is dynamically modulated in a predefined way, a large conversion rate is observed from the carrier signal to the harmonic components, with magnitudes and phases that can be accurately and separately engineered. In addition, by encoding the reflection phases of the meta-atoms, beam scanning for multiple harmonics can be implemented via different digital coding sequences, thus removing the need for intricate phase-shift networks. This work paves the way for efficient harmonic control for applications in communications, radar, and related areas.
关键词： time-domain digital coding metasurface,metasurfaces,radar detection,nonlinear control,harmonic manipulations,wireless communications,beam scanning,biological monitoring
更新于2025-09-10 09:29:36
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Synthesis Algorithm for Near-Field Power Pattern Control and Its Experimental Verification via Metasurfaces
摘要： Antennas and metasurfaces have enabled a number of far-field manipulation functions. According to the addition theorem of multipoles, near fields have richer spatial spectra than far fields, hence in the near-field region it is easier to achieve complex manipulations on field distributions. In this work, an algorithm is presented to synthesize the near fields of source arrays. Given target distributions of near-field intensities and also predefined source magnitudes, the algorithm will find the needed source phases, which can then be applied on active antenna arrays and passive metasurfaces to induce the target distribution of fields. The algorithm adopts the dyadic Green’s function as the propagator, hence it naturally takes account of the near-field and vector properties of electromagnetic fields. As typical application of the algorithm, an example is given to obtain the excitation phases of a dipole array, which is then physically imitated by a coding metasurface. Experimental measurement is performed and the result proves the validity of the algorithm. From the perspective of information metasurface, the algorithm finds the phase-coding pattern of matesurface to achieve specific functions.
关键词： near-field control,Antenna pattern synthesis,computer-generated holography,phase coding,metasurface
更新于2025-09-10 09:29:36
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Using metasurface structures as signal polarisers in microstrip antennas
摘要： This study analyses the influence of a metasurface coupled to a rectangular microstrip antenna. The proposed metasurface converts linearly polarised electromagnetic waves into circularly polarised electromagnetic waves. The rectangular microstrip antenna is designed to operate at 2.45?GHz. The metasurface is coupled to the antenna in order to provide a structure capable of radiating circularly polarised electromagnetic waves without the need for adjustments to the antenna feed. In this analysis, the metasurface was designed from unit cells, distributed in a periodic arrangement acting as a polariser, when coupled to the upper part of the antenna. The geometry of the unit cells and their distribution in the arrangement were calculated in order to obtain an axial ratio below 3?dB in the design frequency range. Prototypes of the microstrip antenna and the metasurface were constructed to obtain experimental results and it was possible to observe a good convergence between the simulated and measured results.
关键词： metasurface,axial ratio,wireless communication,circular polarisation,microstrip antenna
更新于2025-09-10 09:29:36
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Nonlinear Holographic All-Dielectric Metasurfaces
摘要： Nonlinear holographic metasurfaces have been intensively studied due to their potentials in practical applications. So far, nonlinear holographic metasurfaces have only been realized with plasmonic nanoantennas, suffering from high absorption loss and low damage threshold. Herein we propose and experimentally demonstrate a novel mechanism for nonlinear holographic metasurfaces. In contrast to conventional studies, the all-dielectric metasurface is composed of C-shaped Si nanoantennas. The incident laser is enhanced by their fundamental resonance, whereas the generated third-harmonic generation (THG) signals are re-distributed to the air gap region via the higher-order resonance, significantly reducing the absorption loss at short wavelength and resulting in an enhancement factor as high as 230. After introducing abrupt phase changes from 0 to 2π to the C-elements, high-efficiency cyan and blue THG holograms have been experimentally generated with the Si metasurface for the very first time. This research shall shed light on the advances of nonlinear all-dielectric metasurfaces.
关键词： nonlinear hologram,metasurface,all-dielectric metasurface,higher-order resonance
更新于2025-09-09 09:28:46
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Noninterleaved Metasurface for (2 <sup>6</sup> -1) Spin- and Wavelength-Encoded Holograms
摘要： Nanostructured metasurfaces demonstrate extraordinary capabilities to control light at the subwavelength scale, emerging as key optical components to physical realization of multitasked devices. Progress in multitasked metasurfaces has been witnessed in making a single metasurface multitasked by mainly resorting to extra spatial freedom, for example, interleaved subarrays, different angles. However, it imposes a challenge of suppressing the cross-talk among multiwavelength without the help of extra spatial freedom. Here, we introduce an entirely novel strategy of multitasked metasurfaces with noninterleaved single-size Si nanobrick arrays and minimalist spatial freedom demonstrating massive information on 6-bit encoded color holograms. The interference between electric dipole and magnetic dipole in individual Si nanobricks with in-plane orientation enables manipulating six bases of incident photons simultaneously to reconstructed 6-bit wavelength- and spin-dependent multicolor images. Those massively reconstructed images can be distinguished by pattern recognition. It opens an alternative route for integrated optics, data encoding, security encryption, and information engineering.
关键词： 6-bit hologram,spin-wavelength encoding,multitasked metasurface,Noninterleaved metasurface
更新于2025-09-09 09:28:46
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[IEEE 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Espoo, Finland (2018.8.27-2018.9.1)] 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Analysis of Elliptical Aperture Metasurface Antennas
摘要： A Method of Moments (MoM) based analysis is presented for elliptical aperture metasurface (MTS) antennas. The MTS is represented as a sheet transition impedance boundary condition incorporated in a transmission line which accounts for the substrate interaction with the patches layer. The algorithm uses the Fourier-Bessel basis functions (FBBFs) and is inspired from the circular domain analysis. The computation time is then comparable to that of an equivalent size circular aperture MTS. Numerical results obtained with the proposed method are compared with the full wave Contour-FFT (CFFT) based MoM simulation of a MTS implemented with sub-wavelength printed patches.
关键词： Fourier-Bessel basis functions,Method of Moments,Contour-FFT,elliptical aperture,Metasurface antennas
更新于2025-09-09 09:28:46
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THz Sensing With Anomalous Extraordinary Optical Transmission Hole Arrays
摘要： Subwavelength hole array (HA) metasurfaces support the so-called extraordinary optical transmission (EOT) resonance that has already been exploited for sensing. In this work, we demonstrate the superior performance of a different resonant regime of HA metasurfaces called anomalous EOT, by doing a thorough numerical and experimental study of its ability in thin-film label-free sensing applications in the terahertz (THz) band. A comprehensive analysis using both the regular and anomalous EOT resonances is done by depositing thin layers of dielectric analyte slabs of different thicknesses on the structures in different scenarios. We carry out a detailed comparison and demonstrate that the best sensing performance is achieved when the structure operates in the anomalous EOT resonance and the analyte is deposited on the non-patterned side of the metasurface, improving by a factor between 2 and 3 the results of the EOT resonance in any of the considered scenarios. This can be explained by the comparatively narrower linewidth of the anomalous EOT resonance. The results presented expand the reach of subwavelength HAs for sensing applications by considering the anomalous EOT regime that is usually overlooked in the literature.
关键词： metasurface,thin film,anomalous EOT,sensing,terahertz
更新于2025-09-09 09:28:46
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Total-internal-reflection elastic metasurfaces: Design and application to structural vibration isolation
摘要： This letter presents the concept of the Total Internal Reflection metasurface (TIR-MS) which supports the realization of structure-embedded subwavelength acoustic shields for elastic waves propagating in thin waveguides. The proposed metasurface design exploits extreme phase gradients, implemented via locally resonant elements, in order to achieve operating conditions that are largely beyond the critical angle. Such artificial discontinuity is capable of producing complete reflection of the incoming waves regardless of the specific angle of incidence. From a practical perspective, the TIR-MS behaves as a sound hard barrier that is impenetrable to long-wavelength modes at a selected frequency. The TIR metasurface concept is first conceived for a flat interface embedded in a rectangular waveguide and designed to block longitudinal S0-type guided modes. Then, it is extended to circular plates in order to show how enclosed areas can be effectively shielded by incoming waves. Given the same underlying physics, an equivalent dynamic behavior was also numerically and experimentally illustrated for flexural A0-type guided modes. This study shows numerical and experimental evidence that, when the metasurface is excited at the target frequency, significant vibration isolation can be achieved in the presence of waves having any arbitrary angle of incidence. These results open interesting paths to achieve vibration isolation and energy filtering in certain prototypical structures of interest for practical engineering applications.
关键词： elastic waves,TIR-MS,vibration isolation,Total Internal Reflection metasurface,subwavelength acoustic shields
更新于2025-09-09 09:28:46
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Dual-patch Polarization Conversion Metasurface-based Wideband Circular Polarization Slot Antenna
摘要： In this letter, a novel polarization conversion (PC) structure is introduced, and its use with a wideband, wide 3-dB axial-ratio (AR) beam, low-radar-cross-section (RCS) circular polarization (CP) slot antenna is suggested. The unit cell of the proposed PC metasurface (PCM) consists of square and L-shaped patches separated by an L-shaped slot printed on an FR4 substrate. The mechanisms for linear to circular polarization and bandwidth improvement of a conventional antenna are analyzed theoretically. Through numerical optimizations and parametric studies, a simulated 10-dB impedance bandwidth of 42.7% (4.15-6.4 GHz) and a 3-dB AR bandwidth of 26.2% (4.8-6.25 GHz) are achieved by the proposed antenna. As the simulation demonstrates, the proposed antenna achieves an average 20-dB RCS reduction in a wide band from 5.25 to 6.8 GHz compared to a conventional slot antenna covered by the PC band. In addition, compared to previously reported work, the PCM-based CP antenna exhibits a larger 3-dB AR beam width of 200° in the xoz plane and 120° in the yoz plane, and a wider CP bandwidth within the operational bandwidth. Finally, an overall volume of 0.55λ0×0.55λ0×0.05λ0 centered at 5.275 GHz is fabricated and measured, demonstrating good agreement with the simulation results.
关键词： circularly polarized,low RCS,polarization conversion metasurface,dual-patch
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu, China (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Polarization-Controllable Orbital Angular Momentum Using Anisotropic Coding Metasurfaces
摘要： In the past few years, the orbital angular momentum (OAM) has aroused great interests within scientific communities, showing great potentials to enhance capacities in radio, optical and quantum coding metasurface is proposed to generate multiple polarization controllable OAM vortex beams at microwave frequencies. A phase compensation theory is put forward to determine the array pattern of the metasurface, enabling the generation of vortex beams with arbitrary polarization. The metasurface is composed of anisotropic elements, whose reflection phases can be engineered and encoded separately along different polarization directions. The simulation results demonstrate that multiple OAM vortex beams can be generated as expected, with each of them polarized in a controlled manner. The proposed avenue shows great potentials for the application of polarization division multiplexing in OAM communication systems.
关键词： polarization multiplexing,coding metasurface,Orbital angular momentum,radio frequency
更新于2025-09-09 09:28:46