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The investigation of the electromagnetic coupling effect in terahertz toroidal metasurfaces and metamaterials
摘要： We proposed and fabricated toroidal dipole (TD) metasurfaces(MSs) with a metamolecule of two coplanar U-shaped split ring resonators(USRRs) fabricated on polyimide substrate, and TD metamaterials (MMs) were the stacks of two TD MSs layers, whose frequencies, electromagnetic (EM) distributions and Q factor can be efficiently affected by the EM coupling effect in TD MSs/MMs. It was found that the resonances frequencies of TD MMs were shifted to lower frequencies due to the increase of inductance by the stacks of metallic layer. Meanwhile, the high-frequency TD resonance in TD MMs would be tailored by the periodicity. Considering the relation between TD resonances and the scattering power of TD (Ty), the Q factor depended highly on the value of Ty in the same metamolecule structure. The optimization in excitation of TD provide opportunity to further increase the Q-factor of metamaterial and pave a way for potential applications in terahertz sensor and other functional devices.
关键词： Toroidal dipole,Terahertz,Metamaterials,Metasurfaces
更新于2025-09-19 17:13:59
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Investigation of Phonon Scattering on the Tunable Mechanisms of Terahertz Graphene Metamaterials
摘要： The in?uences of di?erent kinds of phonon scatterings (i.e., acoustic (AC) phonon, impurity, and longitudinal optical (LO) phonon scatterings) on the tunable propagation properties of graphene metamaterials structures have been investigated, also including the e?ects of graphene pattern structures, Fermi levels, and operation frequencies. The results manifested that, at room temperature, AC phonon scattering dominated, while with the increase in temperature, the LO phonon scattering increased signi?cantly and played a dominate role if temperature goes beyond 600 K. Due to the phonon scatterings, the resonant properties of the graphene metamaterial structure indicated an optimum value (about 0.5–0.8 eV) with the increase in Fermi level, which were di?erent from the existing results. The results are very helpful to understand the tunable mechanisms of graphene functional devices, sensors, modulators, and antennas.
关键词： terahertz,metamaterials,phonon scatterings,graphene
更新于2025-09-16 10:30:52
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[IEEE 2018 48th European Microwave Conference (EuMC) - Madrid (2018.9.23-2018.9.27)] 2018 48th European Microwave Conference (EuMC) - Dispersion of THz Modes Localized on Layered Superconductor Controlled by DC Magnetic Field
摘要： Being materials that support terahertz waves propagation, layered superconductors attract great attention of many researchers. The Josephson plasma modes localized on a slab of layered superconductor can possess an anomalous dispersion. The possibility of anomalous dispersion manipulation opens wide perspectives for applications. One of the tools that can flexibly change the electromagnetic properties of layered superconductors is the external DC magnetic field. The effect of the DC magnetic field on the spectrum of the localized modes is a subject of the present paper. We present the derivation and analysis of the dispersion relations and discuss some interesting corollaries such as resonant amplification of wave transmission induced by the internal excitation of the localized modes and the possibility of the internal reflection of the localized modes controlled by the external DC magnetic field.
关键词： high-temperature superconductors,electromagnetic fields,Terahertz metamaterials,Josephson junctions
更新于2025-09-12 10:27:22
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Ultrafast Terahertz Frequency and Phase Tuning by All‐Optical Molecularization of Metasurfaces
摘要： The integration of photoactive semiconductors exhibiting strong light–matter interactions into functional unit meta-atoms facilitates effective approaches to dynamically manipulate terahertz (THz) waves. Here, a new metaphotonic modulator is proposed and comprehensively studied, which demonstrates extensive tunability of the resonant frequency and phase with the merit of ultrafast photoswitching. Specifically, parallel silicon (Si) bridges are embedded in metasurfaces to reinforce the connection ability, achieving ultrafast optical molecularization from a magnetic quadrupole into an electric dipole. Under femtosecond pulse excitation, the demonstrated resonant frequency tuning range is as high as 40% (from 1.16 to 0.7 THz) and can be further promoted up to 48% (from 1.56 to 0.81 THz) by varying the Si bridge length. Meanwhile, the phase delay at given frequencies can be controlled up to 53.3° without significantly changing the high transmission. Furthermore, the transient frequency switching and phase shifting dynamics are systematically investigated for the first time, showing a full recovery time within 2 ns. By optically molecularizing metasurfaces, extended tuning ranges with regard to the resonant frequency and phase, as well as an ultrafast switching speed, are simultaneously acquired in the proposed metamodulator, which provides deeper insight into the multifunctional active-tuning systems.
关键词： silicon microstructures,ultrafast photoswitching,terahertz metamaterials,molecularization
更新于2025-09-11 14:15:04