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Realization of a three-dimensional photonic topological insulator
摘要： Confining photons in a finite volume is highly desirable in modern photonic devices, such as waveguides, lasers and cavities. Decades ago, this motivated the study and application of photonic crystals, which have a photonic bandgap that forbids light propagation in all directions1–3. Recently, inspired by the discoveries of topological insulators4,5, the confinement of photons with topological protection has been demonstrated in two-dimensional (2D) photonic structures known as photonic topological insulators6–8, with promising applications in topological lasers9,10 and robust optical delay lines11. However, a fully three-dimensional (3D) topological photonic bandgap has not been achieved. Here we experimentally demonstrate a 3D photonic topological insulator with an extremely wide (more than 25 per cent bandwidth) 3D topological bandgap. The composite material (metallic patterns on printed circuit boards) consists of split-ring resonators (classical electromagnetic artificial atoms) with strong magneto-electric coupling and behaves like a ‘weak’ topological insulator (that is, with an even number of surface Dirac cones), or a stack of 2D quantum spin Hall insulators. Using direct field measurements, we map out both the gapped bulk band structure and the Dirac-like dispersion of the photonic surface states, and demonstrate robust photonic propagation along a non-planar surface. Our work extends the family of 3D topological insulators from fermions to bosons and paves the way for applications in topological photonic cavities, circuits and lasers in 3D geometries.
关键词： 3D photonic topological insulator,split-ring resonators,Dirac surface states,robust photonic propagation,topological bandgap
更新于2025-09-23 15:23:52
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Analytical model of the fundamental mode of 3D square split ring resonators
摘要： An analytical model is developed for the charge and potential distributions of the fundamental mode of three-dimensional (3D) singly split ring resonators (SRRs) with square cross section, which nowadays can be conveniently fabricated by additive manufacturing techniques. This model allows the derivation of approximate formulas for the equivalent capacitance and the analysis of the resonant properties of this type of SRRs at any frequency. The total capacitance is expressed as the sum of the usual gap capacitance and a surface capacitance associated with the charges on the SRR walls, which are determined from the solution for the irrotational part of the electric field of a square split cylinder obtained by conformal mapping. The applicability of the proposed model for a broad range of SRR parameters is demonstrated by comparing the resonance frequency of sample SRR configurations found theoretically with the corresponding values obtained by numerical simulations and experiments. Furthermore, the functions describing the charge and current mode profiles provided in this work can be instrumental in estimating the near-field interaction and the coupling constants of an ensemble of resonant 3D square split rings and thus for tailoring the response of metamaterials and other devices formed by these elements.
关键词： capacitance,resonance frequency,analytical model,split ring resonators,metamaterials
更新于2025-09-23 15:22:29
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PERFORMANCE IMPROVEMENT OF PATCH ANTENNA USING CIRCULAR SPLIT RING RESONATORS AND THIN WIRES EMPLOYING METAMATERIALS LENS
摘要： In this paper, the left-handed metamaterial which acts as a lens is employed to improve the performance of a microstrip patch antenna. The left-handed metamaterial used in this work is a three-dimensional periodic structure which consists of circular split ring resonators and thin wires. The three-dimensional periodic metamaterial structure shows angular independency characteristics in wide range angles, so it acts as a metamaterial lens. However, the MTM structure in?nite periodicity truncation has no impacts on the MTM lens scattering, e?ective parameters and homogeneity. The left-handed metamaterial is placed in front of the microstrip patch antenna and due to the negative refractive index property of the left-handed metamaterial; the radiated electromagnetic beam size decreases which results in a highly focused beam. The proposed antenna has been designed and simulated using CST microwave studio, and the metamaterial e?ective parameters are extracted from the S parameters by using Nicolson-Ross-Weir algorithm and by selecting the appropriate ambiguity branch parameter. Furthermore, the angular independency of the metamaterial lens has been veri?ed by rotating the metamaterial structure with respect to the excitation probe of the transverse electromagnetic waves and extracting the S-parameters and the e?ective parameters for each rotation angle. A parametric analysis has been performed to study the e?ects of the patch antenna and left-handed metamaterial lens separation and the size of the three-dimensional left-handed metamaterial structure on the radiating properties and the impedance matching of the proposed antenna. For the experimental veri?cation, the proposed antenna operating at 10 GHz is fabricated; the return loss, radiation pattern and gain for the proposed antenna with and without metamaterial are measured. Furthermore, the results show that the antenna gain is improved by 4.6 dB which validates the concept of beam focusing using negative refractive index metamaterial structure, while the return loss and bandwidth are slightly reduced. The simulation and experiment investigated the idea of the beam focusing using negative refractive index metamaterial lens in microwave regime.
关键词： microstrip patch antenna,CST microwave studio,beam focusing,Nicolson-Ross-Weir algorithm,parametric analysis,left-handed metamaterial,circular split ring resonators,negative refractive index,angular independency,experimental verification,thin wires
更新于2025-09-23 15:21:01
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Invited Article: Emission of intense resonant radiation by dispersion-managed Kerr cavity solitons
摘要： We report on an experimental and numerical study of temporal Kerr cavity soliton dynamics in dispersion-managed fiber ring resonators. We find that dispersion management can significantly magnify the Kelly-like resonant radiation sidebands emitted by the solitons. Because of the underlying phase-matching conditions, the sideband amplitudes tend to increase with increasing pump-cavity detuning, ultimately limiting the range of detunings over which the solitons can exist. Our experimental findings show excellent agreement with numerical simulations.
关键词： phase-matching conditions,temporal Kerr cavity solitons,dispersion-managed fiber ring resonators,pump-cavity detuning,resonant radiation sidebands
更新于2025-09-23 15:21:01
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SRR LOADED COMPACT UHF RFID TAG FOR BROADBAND OPERATION
摘要： An SRR loaded compact RFID tag for broadband operation over the UHF RFID band is presented. The tag antenna structure is composed of a dipole whose arms are symmetrically loaded with square split ring resonators (SRRs) along a short circuited strip between the SRRs. The antenna is made inductive and reduced in overall size by the SRR sections. The measured read range characteristics of the proposed RFID tag with an RFID chip Alien Higgs-3 are presented. The proposed tag operates over the entire UHF RFID band about a maximum read range of 7 meters in the entire elevation angular ranges and over wide azimuthal angular ranges.
关键词： square split ring resonators,read range,compact RFID tag,dipole antenna,broadband operation,UHF RFID band,SRR
更新于2025-09-23 15:21:01
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2D Layered Graphene Oxide Films Integrated with Microa??Ring Resonators for Enhanced Nonlinear Optics
摘要： Layered 2D graphene oxide (GO) films are integrated with micro-ring resonators (MRRs) to experimentally demonstrate enhanced nonlinear optics. Both uniformly coated (1?5 layers) and patterned (10?50 layers) GO films are integrated on complementary-metal-oxide-semiconductor (CMOS)-compatible doped silica MRRs using a large-area, transfer-free, layer-by-layer GO coating method with precise control of the film thickness. The patterned devices further employ photolithography and lift-off processes to enable precise control of the film placement and coating length. Four-wave-mixing (FWM) measurements for different pump powers and resonant wavelengths show a significant improvement in efficiency of ≈7.6 dB for a uniformly coated device with 1 GO layer and ≈10.3 dB for a patterned device with 50 GO layers. The measurements agree well with theory, with the enhancement in FWM efficiency resulting from the high Kerr nonlinearity and low loss of the GO films combined with the strong light–matter interaction within the MRRs. The dependence of GO’s third-order nonlinearity on layer number and pump power is also extracted from the FWM measurements, revealing interesting physical insights about the evolution of the GO films from 2D monolayers to quasi bulk-like behavior. These results confirm the high nonlinear optical performance of integrated photonic resonators incorporated with 2D layered GO films.
关键词： four-wave mixing,graphene oxide,micro-ring resonators,integrated optics,Kerr nonlinearity,2D materials
更新于2025-09-23 15:19:57
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Free-Standing Complementary Asymmetric Metasurface for Terahertz Sensing Applications
摘要： We designed and tested a highly sensitive metasurface device based on free-standing complementary asymmetric split-ring resonators at terahertz frequencies. It is utilized for sensing a galactose film. We characterized the device using the induced red shift of a Fano resonance observed in the THz transmission. The sensor has a high sensitivity of 91.7 GHz/RIU due to a significant interaction between the galactose overlayer and the metasurface.
关键词： terahertz,asymmetric split-ring resonators,sensing,free-standing
更新于2025-09-23 15:19:57
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Coupling thermal atomic vapor to an integrated ring resonator
摘要： Strongly interacting atom–cavity systems within a network with many nodes constitute a possible realization for a quantum internet which allows for quantum communication and computation on the same platform. To implement such large-scale quantum networks, nanophotonic resonators are promising candidates because they can be scalably fabricated and interconnected with waveguides and optical fibers. By integrating arrays of ring resonators into a vapor cell we show that thermal rubidium atoms above room temperature can be coupled to photonic cavities as building blocks for chip-scale hybrid circuits. Although strong coupling is not yet achieved in this first realization, our approach provides a key step towards miniaturization and scalability of atom–cavity systems.
关键词： atom–cavity systems,ring resonators,integrated optics,atomic vapor spectroscopy
更新于2025-09-23 15:19:57
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[IEEE 2018 18th Mediterranean Microwave Symposium (MMS) - Istanbul, Turkey (2018.10.31-2018.11.2)] 2018 18th Mediterranean Microwave Symposium (MMS) - Chiral SRR Metasurfaces for Circular Polarisation Conversion
摘要： A circular polarization dual band metamaterial polarization rotator composed of two double split ring resonators rotated 90o with respect to each other is presented. Asymmetric transmission between Txx and Tyy and symmetric transmission between Txy and Tyx has been achieved. The circular polarization is caused by the symmetric transmission between Txy and Tyx. The design has been demonstrated numerically at microwaves frequency. The structure holds promise for ultra-compact polarizing devices for any frequency range given the scalability of the approach.
关键词： Metasurfaces,Circular polarization,Chiral metamaterial,Split Ring Resonators
更新于2025-09-19 17:15:36
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Numerical and Theoretical Study of Tunable Plasmonically Induced Transparency Effect Based on Brighta??Dark Mode Coupling in Graphene Metasurface
摘要： In this paper, we numerically and theoretically study the tunable plasmonically induced transparency (PIT) effect based on the graphene metasurface structure consisting of a graphene cut wire (CW) resonator and double split-ring resonators (SRRs) in the middle infrared region (MIR). Both the theoretical calculations according to the coupled harmonic oscillator model and simulation results indicate that the realization of the PIT effect significantly depends on the coupling distance and the coupling strength between the CW resonator and SRRs. In addition, the geometrical parameters of the CW resonator and the number of the graphene layers can alter the optical response of the graphene structure. Particularly, compared with the metal-based metamaterial, the PIT effect realized in the proposed metasurface can be flexibly modulated without adding other actively controlled materials and reconstructing the structure by taking advantage of the tunable complex surface conductivity of the graphene. These results could find significant applications in ultrafast variable optical attenuators, sensors and slow light devices.
关键词： plasmonically induced transparency effect,metasurface,mid-infrared region,graphene split-ring resonators,graphene cut wire resonator
更新于2025-09-19 17:13:59