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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Active Metasurface Devices for Terahertz Wave Front Modulation
摘要： Terahertz (THz) radiation, which is sandwiched between the infrared and microwave in the electromagnetic spectrum, has become more and more attractive due to its special properties. Compared with the quick development of THz sources and detectors, THz functional devices are lagging behind, especially the devices for wave front modulation. Metasurface, a kind of artificial materials, is enable effective manipulation of the amplitude, phase and polarization state of electromagnetic waves with subwavelength spatial resolution. It has been used for ultrathin planar lenses, complex light field generation, spin orbital angular momentum coupling, and metasurface holograms. However, the function of this kind of metasurface based devices are fixed once they are fabricated, the spatial THz modulation which can dynamically modulate the wave front of THz radiation is demand in high resolution THz imaging and THz communication. In this presentation, we present a novel approach for generating arbitrary wave fronts of a THz beam by dynamically creating metasurface structures through illuminating a super thin silicon wafer with femtosecond laser, which is spatially modulated to result in an array of reconfigurable subwavelength resonators. The wave front of the THz beam is then determined by forming spatial profiles of the Pancharatnam-Berry scattering phase by dynamically controlling the resonator orientation. Proof-of-concept experiments demonstrate that streaming holographic images and lenses of variable focal length can be realized in real time. The theoretical expectations and experimental results are shown in Fig. 1, the generated patterns are matching with the theoretical exceptions. The reconfigurable scheme demonstrated here is convenient and fast, and may lead to advances in a host of THz applications.
关键词： Pancharatnam-Berry scattering phase,reconfigurable subwavelength resonators,wave front modulation,metasurface,Terahertz
更新于2025-09-12 10:27:22
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Holey metasurface prism for the reduction of the dispersion of gap waveguide leaky-wave antennas
摘要： Leaky-wave antennas (LWA) are dispersive, meaning that the direction of maximum radiation is a function of frequency. This behavior, called “beam squinting effect” can be reduced by introducing a dispersive metamaterial prism. In this paper a holey metasurface prism is combined with a leaky-wave antenna in gap waveguide technology. The dispersion characteristics of the hole unit cell are studied in order to achieve the reduction of the main beam steering aiming to ±1o or less variation. A prototype designed at the Ka band is measured and compared with the simulation results.
关键词： groove gap waveguide,leaky-wave antenna,metasurface prism,dispersive radiation pattern
更新于2025-09-12 10:27:22
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Meta-waveguide analysis and implementation for using as a slot array antenna
摘要： This paper presents a novel concept named meta-waveguide structures to design slot array antennas based on metasurface. The proposed method investigates the geometrical parameters of the embedded metasurface and their relations to build up the engineered electric and magnetic fields to introduce efficient slot array antennas. This approach eliminates the necessity of using the well-known offsets in typical slot arrays, which can be benefited from linear array theorem. This idea is realized by employing successive filed curvature along the propagation direction, utilizing periodic metasurfaces. Thereafter, a step-by-step algorithm is recommended to design an efficient slot array antenna. Finally, a prototype is fabricated and tested experimentally validating the theoretical calculations.
关键词： Metasurface,slot array antenna,slot waveguide array,meta-waveguide
更新于2025-09-11 14:15:04
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Accurate and Robust Characterization of Metasurface-Enabled Frequency Reconfigurable Antennas by Radially Homogeneous Model
摘要： A category of frequency recon?gurable antennas realized by rotating mechanically a meta- surface mounted atop a source radiator has attracted growing attention. Their electromagnetic properties and range of frequency recon?gurability have, nevertheless, not been satisfactorily studied. To this end, an equivalent radially homogeneous model is ?rstly proposed in this paper. The retrieval process is accordingly formulated to address the polarization dependence of the retrieved effective electromagnetic parameters. A couple of typical metasurface-based frequency mechanically recon?gurable antennas are thus characterized by the proposed model. The predicted central operating frequencies are validated against the results of full-wave simulation and the measurement ones of manufactured proof-of-concept prototypes. Further comparisons to the isotropic and the anisotropic models con?rm superior accuracy, robustness, and simplicity of the proposed characterization model. In addition, frequency recon?gurable range is shown to be determined by the anisotropy of the metasurface, related to the geometrical symmetry of its constitutive unit cell.
关键词： electromagnetic homogenization,anisotropic model,NRW,Metasurface
更新于2025-09-11 14:15:04
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Optimized Chemical Potential Graphene-Based Coding Metasurface Approach for Dynamic Manipulation of Terahertz Wavefront
摘要： In this paper, a new method for the design of pixelated graphene-based coding metasurface is proposed. This method suggests a straightforward approach by utilizing graphene tunable pixels (GTP), which can control the reflection phase in a real-time manner at terahertz (THz) frequencies. The proposed unit cell is composed of four distinct graphene patches in the same layer, which has a chemical potential that obtained by utilizing optimization-based methods. By changing the reflection phase profile across the metasurface, the proposed device can manipulate the reflected wave phase, amplitude, and polarization control in various beamforming applications at THz spectrum for modern information systems, data encryption, and THz communication applications. Chemical potential optimization method in graphene-based coding metasurface is not limited to a specific structure for phase-only metasurface. Indeed it has an exceptional capability for metasurface to manipulate electromagnetic (EM) wave in the half-space and generate converged vortex beam, non-diffractive Bessel beam, and EM bump illusion. The simulation and theoretical results show that the suggested method offers a feasible strategy for multifunctional metasurface applications.
关键词： Bessel beam,Illusion,Chemical potential optimization,Vortex beam,Metasurface,Graphene
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Robust Polarimetry with a Single Metagrating
摘要： One-shot optical polarimetry using ultra-thin nanostructured metagratings opens up new opportunities for diverse applications, facilitating the measurement of both classical and quantum polarization states. Despite the significant progress, there appeared fundamental limitations associated with a need to interleave multiple metagratings on a metasurface in order to split several distinct pairs of polarization components, which limited diffraction efficiency and negatively affected the beam quality. A recent study demonstrated polarimetry with a single metagrating, however it required an additional linear polarizer with the associated detrimental effects of attenuating the detected optical power, reducing the device compactness, and increasing the setup complexity. We formulate a new conceptual approach for polarization measurements with a single metagrating, which allows us to overcome the limitations that were inherent to the previous schemes. We find that those limitations occurred due to the attempts of replicating traditional polarimetry based on close-to-perfect polarizers, where each measurement characterizes a definite polarization component. Yet in general, metasurfaces can behave like sets of imperfect (partial) polarizers, and it is our key finding that full Stokes polarization reconstruction is possible in this regime. Specifically, we develop a rigorous polarimetry approach based on the positive operator-valued measure (POVM) formalism originating from quantum mechanics. This fundamentally lifts the restrictions on metasurface design and enables robust operation even under significant fabrication inaccuracies.
关键词： metagrating,polarization reconstruction,polarimetry,metasurface,POVM
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Semi-Analytic Modeling of Chiral Metasurface Stacks
摘要： Metasurfaces allow anisotropic polarization states to be designed freely from the geometry, material and distribution of their constituent subwavelength structures or particles as well as their arrangement. It was shown recently that multilayer metasurfaces can exhibit a chiral polarization response without having chiral particles or near-field induced bianisotropy. Such stacked metasurfaces couple modally in the far-field and are geometrically chiral only as a complete system, even though their constituent parts are not. In our contribution we employ a semi-analytic approach to derive a model of a chiral metasurface stack consisting of two nano-wire based metasurfaces with rotated unit cells, separated by a spacer layer. Using a fabricated sample as a basis for our discussion, we explain the origin of its polarization response and unravel the role of the spacer layer separating the two metasurfaces.
关键词： chiral metasurface,spacer layer,semi-analytic modeling,nano-wire,polarization response
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - All-Dielectric High-Q Metasurfaces for Infrared Absorption Spectroscopy Applications
摘要： The mid-infrared (mid-IR) spectral range is crucial for spectroscopic investigations of biological systems since it contains the characteristic absorption signatures (i.e., the molecular ‘fingerprints’) of chemical and biological analytes, which are uniquely determined by the vibrational modes and associated absorption bands of its chemical bonds. Here we present a novel nanophotonics-based approach for detecting molecular fingerprints, which utilizes imaging-based methods to provide spectrometer-less operation in a miniaturized sensor device ideally suited for analyzing complex biological systems. The central building block of this technique is a pixelated dielectric metasurface where the individual metapixels are engineered to provide sharp resonances at a given resonance frequency. Each metapixel is made out of specifically designed zig-zag resonator arrays, which employ the concept of bound states in continuum to create high-Q resonances. The detection performance of the experimentally realized metasurface sensor was demonstrated by interrogating a monolayer of recombinant protein A/G molecules, which reveals the characteristic amide I and amide II absorption bands as distinct regions with attenuated peak reflectance of the resonances. A comparison of the total reflectance signals of all the metapixels before and after material adsorption delivers a distinct barcode pattern which can be used for chemically specific molecule detection. Importantly, this molecular barcoding method operates under broadband illumination and detection conditions, meaning that the chemically specific signals can be obtained without the need for spectrometry.
关键词： high-Q resonances,dielectric metasurface,nanophotonics,molecular barcoding,mid-infrared,molecular fingerprints
更新于2025-09-11 14:15:04
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[IEEE 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Berlin, Germany (2019.6.23-2019.6.27)] 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Micromachined Uncooled Si <sub/>x</sub> Ge <sub/>y</sub> O <sub/>1-x-y</sub> Microbolometer Integrated Metasurface for Uncooled Infrared Detection
摘要： This paper presents a study of metasurface integrated uncooled infrared (IR) silicon germanium oxide (Si-Ge-O) microbolometers for Long Wavelength Infrared (LWIR) detection. The inclusion of the metasurface permits engineering the IR absorptance with respect to wavelength. Absorption by the metasurface eliminates the need for a ?- wave resonant cavity under the microbolometer. In addition, the metasurface can significantly improve the electrical performance of the temperature-sensing layer. Experimental results show an increase in the Temperature Coefficient of Resistance (TCR) and a decrease in the resistivity of the amorphous Si-Ge-O films. These parameters scale with the periodicity and area fraction of the metasurface. The voltage noise power spectral density was reduced by annealing the devices in vacuum. The measured responsivity and detectivity approached 104 V/W and 109 cm Hz1/2/W to filtered blackbody infrared radiation.
关键词： Infrared detector,Metasurface,TCR,Si-Ge-O,Microbolometer,Noise
更新于2025-09-11 14:15:04
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Progresses in the practical metasurface for holography and lens
摘要： Metasurfaces have received enormous attention thanks to their unique ability to modulate electromagnetic properties of light in various frequency regimes. Recently, exploiting its fabrication ease and modulation strength, unprecedented and unique controlling of light that surpasses conventional optical devices has been suggested and studied a lot. Here, in this paper, we discuss some parts of this trend including holography, imaging application, dispersion control, and multiplexing, mostly operating for optical frequency regime. Finally, we will outlook the future of the devices with recent applications of these metasurfaces.
关键词： metasurface,flat optics,metamaterial
更新于2025-09-11 14:15:04