In this letter, we propose a structure based on double-layer graphene-based planar chiral metasurface with a J-shaped pattern to generate asymmetric transmission for circularly polarized waves in the mid-infrared region. Asymmetric transmission of the double-layer structure can reach to 16.64%, which is much larger than that of the monolayer. The mechanism of asymmetric transmission is attributed to enantiomerically sensitive graphene's surface plasmons. Besides, asymmetric transmission can be dynamically tuned by changing the Fermi energy and is affected by intrinsic relaxation time. All simulations are conducted by the finite element method. Our findings provide a feasibility of realizing photonic devices in tunable polarization-dependent operation, such as asymmetric wave splitters and circulators.
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http://dx.doi.org/10.1039/c9ra05760a | DOI Listing |
Micromachines (Basel)
December 2024
College of Electronic and Electrical Engineering, Henan Normal University, Xinxiang 453600, China.
A novel common-aperture miniaturized antenna with wideband and dual-polarized characteristics is proposed, which consists of a circularly polarized (CP) and a linearly polarized (LP) antenna. The circularly polarized antenna stacked on the upper layer adopts asymmetrical ground and introduces the patch and T-type feed network. On this basis, the meshed reflector structure, which also works as a ground plane for the LP antenna, is added to reduce the influence on circular polarization and achieve directional radiation.
View Article and Find Full Text PDFNat Mater
January 2025
Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA.
Van der Waals materials display rich structural polymorphs with distinct physical properties. An atomistic understanding of the phase-transition dynamics, propagation pathway and associated evolution of physical properties is essential for capturing their potential in practical technologies. However, direct visualization of the rapid phase-transition process is fundamentally challenging due to the inherent trade-offs among atomic resolution, field of view and imaging frame rate.
View Article and Find Full Text PDFChem Sci
January 2025
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences Fuzhou 350002 China
Traditional tetrahedral-based mid-to-far infrared (MFIR) nonlinear optical (NLO) crystals often face limitations due to the optical anisotropy constraints imposed by their highly symmetric structures. In contrast, the relatively rare trigonal pyramidal [TeS] functional unit characterized by its asymmetric structure and stereochemically active lone pair (SCALP), offers improved optical anisotropy, hyperpolarizability and a broader IR transparency range. Despite its potential, synthetic challenges have hindered the development of MFIR NLO crystals that incorporate this unit, with only one example reported to date.
View Article and Find Full Text PDFFront Neurosci
January 2025
School of Electronic Information and Communications, Huazhong University of Science and Technology, Wuhan City, China.
Introduction: Transcranial magnetic stimulation (TMS) is widely used for the noninvasive activation of neurons in the human brain. It utilizes a pulsed magnetic field to induce electric pulses that act on the central nervous system, altering the membrane potential of nerve cells in the cerebral cortex to treat certain mental diseases. However, the effectiveness of TMS can be compromised by significant heat generation and the clicking noise produced by the pulse in the TMS coil.
View Article and Find Full Text PDFNat Commun
January 2025
Department of Physics, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan.
Bending loss is one of the serious problems for constructing nanophotonic integrated circuits. Recently, many works reported that valley photonic crystals (VPhCs) enable significantly high transmission via 120-degree sharp bends. However, it is unclear whether the high bend-transmission results directly from the valley-photonic effects, which are based on the breaking of inversion symmetry.
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