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- 2018
- arbitrary coupling coefficients
- Dielectric resonator
- filtering
- coupler
- filtering balun
- dual-band
- dual-mode dielectric resonator (DR)
- Electronic Science and Technology
- Nantong University
- Sun Yat-Sen University
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Towards silicon-based metamaterials
摘要： We study periodic lattices of silicon nanorods and introduce the concept of a phase diagram that characterizes a transition between the regimes of photonic crystals and dielectric metamaterials when the lattice spacing and operational wavelength vary. We find the conditions when a hexagonal periodic lattice of silicon nanorods can operate as a metamaterial described by averaged parameters. In general, we reveal that the metamaterial regime can be achieved for dielectric permittivity exceeding the value ε = 14, being commonly available for semiconductors in both visible and near-infrared frequency ranges. Thus, advanced semiconductor technologies can offer a versatile platform for novel designs of all-dielectric Mie-resonant metadevices.
关键词： phase diagram,photonic crystals,dielectric metamaterials,Mie resonances,silicon nanorods
更新于2025-09-23 15:21:21
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Dielectric and piezoelectric properties of Sm3+ doped lead barium niobate (PBN) ceramics
摘要： Rhombohedral samarium doped Lead based ceramic materials were fabricated by a high temperature conventional solid state mixed oxide ceramic process. The ceramic composition Pb1-x-3y/2Bax Re3+ y Nb2O6 (x = 0.35 and y=0.00, 0.02, 0.04 and 0.06, Re3+ = Sm3+). The pure and Sm3+ doped lead barium niobate ceramic materials are single phase with rhombohedral(hexagonal) symmetry obtained from powder x-ray diffraction (XRD). The grain size has been measured for all the compositions and lying between 1.60-2.90μm. Broad dielectric peak phase transitions observed with temperature in pure and Sm3+ ion modified lead barium niobate ceramic materials. It is observed that the high values of piezoelectric charge coefficients in d31 and d33 in Sm3+ doped lead barium niobate ceramics. The mechanical quality factor Qm and d33 increases with increase of Sm3+ ion concentration and indicating a highly polarisable lead ion contributing to high Curie temperature dielectric constant.
关键词： SEM,Piezoelectric properties,Rhombohedral,Synthesis of ceramic compositions,dielectric,X-Ray diffraction
更新于2025-09-23 15:21:21
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Nonperturbative nonlinear effects in the dispersion relations for TE and TM plasmons on two-dimensional materials
摘要： We analytically obtain the dispersion relations for transverse-electric (TE) and transverse-magnetic (TM) surface plasmon-polaritons in a nonlinear two-dimensional (2D) conducting material with inversion symmetry lying between two Kerr-type dielectric media. To this end, we use Maxwell’s equations within the quasielectrostatic, weakly dissipative regime. We show that the wavelength and propagation distance of surface plasmons decrease due to the nonlinearity of the surrounding dielectric. In contrast, the effect of the nonlinearity of the 2D material depends on the signs of the real and imaginary parts of the third-order conductivity. Notably, the dispersion relations obtained by naively replacing the permittivity of the dielectric medium by its nonlinear counterpart in the respective dispersion relations of the linear regime are not accurate. We apply our analysis to the case of doped graphene and make predictions for the surface plasmon wavelength and propagation distance.
关键词： Maxwell’s equations,quasielectrostatic regime,weakly dissipative regime,nonlinear two-dimensional materials,surface plasmon-polaritons,doped graphene,Kerr-type dielectric media
更新于2025-09-23 15:21:21
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Characterization of the lossy dielectric materials using contour mapping
摘要： The imaginary part of the complex permittivity of a lossy dielectric material is large and couples with its real part. The resonant frequency of a cavity with the sample depends not only on the real part of the complex permittivity of the sample but also the imaginary part, resulting in serious ambiguity in determining the sample’s complex permittivity. This work proposes a contour mapping method to determine the complex permittivity. The full-wave simulation gives us the contours of the resonant frequency and the quality factor, which are functions of the relative dielectric constant and the loss tangent. By mapping the measured resonant frequency and the measured quality factor, one can uniquely determine the complex permittivity of the sample. Five liquids were examined, including three low-loss materials for benchmarking and two lossy materials. The measured complex permittivities of the three low-loss materials agree very well with the other methods. As for the lossy materials, the measured relative dielectric constant and the loss tangent of alcohol are 6.786 and 0.895, respectively. Besides, the measured dielectric constant of glycerin is 6.811, and its loss tangent is 0.562. The proposed contour mapping technique can be employed to measure the complex permittivity of liquids and solids from lossless to lossy materials.
关键词： lossy dielectric materials,resonant frequency,contour mapping,complex permittivity,quality factor
更新于2025-09-23 15:21:21
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[IEEE 2018 Second International Conference on Advances in Electronics, Computers and Communications (ICAECC) - Bangalore (2018.2.9-2018.2.10)] 2018 Second International Conference on Advances in Electronics, Computers and Communications (ICAECC) - A comparitive study on the performance of circular patch antenna using low cost substrate for S-band applications
摘要： This paper focusses on comparison of the performance of Circular Microstrip Patch Antenna(CMPA) in S-band between CMPA with soil as substrate and CMPA with RT/Duroid 5880 as substrate. RT/Duroid 5880 is commonly used in the fabrication of Microstrip Patch Antennas (MPA) due to its low electrical loss, low dielectric loss, low moisture absorption etc. However, it is costly. This work tries to prove that soil substrate can be one of the contenders in the future to replace RT/Duroid 5880. The simulation is carried out in Computational Electromagnetic Software FEKO (suite 7.0). The paper concludes by stating that soil substrate being economical can be a potential candidate to replace RT/Duroid 5880 as there is very little to minimal change in key parameters such as bandwidth (a difference of 14.07 MHz), gain (a difference of 0.18 dBi) and directivity (a difference of 0.41 dBi) when the simulation results are compared.
关键词： antenna,patch,increasing gain,FEKO,dielectric constant,circular microstrip,enhancement of bandwidth
更新于2025-09-23 15:21:21
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A single-cell-gap transflective liquid crystal display with a vertically aligned cell
摘要： A single-cell-gap transflective liquid crystal display with a vertically aligned cell using square ring electrode is demonstrated. The top substrate has a top planar common electrode, a square ring pixel electrode is coated on the bottom substrate, while a bumpy reflector is coated under the bottom substrate. In this device, the planar common electrode and square ring pixel electrode generate a strong longitudinal electric field in the transmissive region (T region) and a weak fringe field in the reflective region (R region). As result, the T and R regions accumulate the same optical phase retardation. The simulation results show that the display exhibits reasonably low operating voltage, high transmittance and well-matched voltage-dependent transmittance and reflectance curves. Besides, fabrication process of the transflective liquid crystal display is very simple.
关键词： square ring electrode,Vertically aligned cell,negative dielectric anisotropy,single-cell-gap,transflective liquid crystal display
更新于2025-09-23 15:21:21
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Highly tunable multiple narrow emissions of dyed dielectric-metal core-shell resonators: towards efficient fluorescent labels
摘要： We report a potential efficient fluorescent label based on the dyed dielectric-metal core-shell resonators. By utilizing the near-field coupling between the dyes and the multipolar sharp cavity plasmon resonances, the dyed dielectric-metal core-shell resonators with diameter of 1.02 μm are demonstrated to be capable of supporting multiple spontaneous emission peaks with the linewidths as narrow as ~ 10 nm in visible range, and these reshaped fluorescent emissions are insensitive to the surrounding dielectric environment. Furthermore, these multiple narrow emission peaks show a precise tunability on the spectrum by simply separating a nanometric dielectric layer between the dielectric core and the metallic shell, which may provide an attractive spectral multiplexing strategy in the fields of cell biology and medical sciences.
关键词： spectral multiplexing,cavity plasmons,fluorescent label,dyed dielectric-metal core-shell resonators,quality factor
更新于2025-09-23 15:21:21
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Avoided crossings and bound states in the continuum in low-contrast dielectric gratings
摘要： We consider bound states in the continuum (BICs) in low-contrast dielectric gratings. It is demonstrated that the BICs originate from the reduced guided modes on the effective dielectric slab with the permittivity equal to the average permittivity of the dielectric grating. In the case of isolated resonances, the positions of BICs can be found from two-wave dispersion relationships for guided leaky modes. In the case of the degeneracy between the two families of leaky modes, the system exhibits an avoided crossing of resonances. In the spectral vicinity of the avoided crossing the transmittance as well as the emergence of BICs is described in the framework of the generic formalism by Volya and Zelevinsky [Phys. Rev. C 67, 054322 (2003)] with a single fitting parameter.
关键词： leaky modes,dielectric gratings,bound states in the continuum,avoided crossings
更新于2025-09-23 15:21:21
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Aperiodic order induced enhancement of weak nonlocality in multilayered dielectric metamaterials
摘要： Recent studies on fully dielectric multilayered metamaterials have shown that the negligibly small nonlocal effects (spatial dispersion) typically observed in the limit of deeply subwavelength layers may be significantly enhanced by peculiar boundary effects occurring in certain critical parameter regimes. These phenomena, observed so far in periodic and randomly disordered geometries, are manifested as strong differences between the exact optical response of finite-size metamaterial samples and the prediction from conventional effective-theory-medium models based on mixing formulas. Here, with specific focus on the Thue-Morse geometry, we make a first step toward extending the studies above to the middle ground of aperiodically ordered multilayers, lying in between perfect periodicity and disorder. We show that, also for these geometries, there exist critical parameter ranges that favor the buildup of boundary effects leading to strong enhancement of the (otherwise negligibly weak) nonlocality. However, the underlying mechanisms are fundamentally different from those observed in the periodic case and exhibit typical footprints (e.g., fractal gaps, quasilocalized states) that are distinctive of aperiodic order. The outcomes of our study indicate that aperiodic order plays a key role in the buildup of the aforementioned boundary effects and may also find potential applications to optical sensors, absorbers, and lasers.
关键词： absorbers,optical sensors,lasers,Thue-Morse geometry,aperiodic order,multilayered dielectric metamaterials,nonlocality
更新于2025-09-23 15:21:21
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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) - Dual-Band Filtering Balun Based on Dual-Mode Dielectric Resonator
摘要： In this paper, a dual-mode dielectric resonator (DR) is investigated and utilized to design filtering balun with dual-band response. The properties of the dual-mode DR are analyzed in detail. According to the field distributions, the two modes can be simultaneously extracted as out-of-phase signals for differential applications. A dual-band filtering balun is designed, fabricated and measured, showing good performance of amplitude balance and 180o phase difference. Good agreement can be obtained between their respective simulated and measured results.
关键词： filtering balun,dual-band,dual-mode dielectric resonator (DR)
更新于2025-09-23 15:21:21