- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[IEEE 2018 International Conference on Communication and Signal Processing (ICCSP) - Chennai (2018.4.3-2018.4.5)] 2018 International Conference on Communication and Signal Processing (ICCSP) - Envelope Modification of the Hyperbolic Frequency Modulated Signal with LC-Filters in order to have a Better Range Resolution in Radar Systems
摘要： The theme of this paper is to realize a continuous time domain window similar to the Hamming window. Windowing is used in signal processing to smooth the spectral content and for reducing the spectral leakage as well. Long time duration windows with narrow spectral content can provide much better smoothing compared with short duration windows with broad spectral content. The other advantage of the windowing in the time domain is the reduction of sidelobe levels in the output of the matched filter (MF). In radar systems which use the MF, this reduction in the relative sidelobe level improves the resolution of the system. Radar systems use the hyperbolic frequency modulated (HFM) signals to have the better range and velocity resolutions since these waveforms are Doppler invariant. To further improve the range resolution, the envelope of the HFM signal has been modified using a continuous time domain Hamming window and its Doppler invariant property has been observed. In order to realize the practical circuit that implements the analogous continuous time domain Hamming window for the HFM signal, Butterworth notch filter, and Butterworth highpass filters (HPF) has been considered and it is observed that HPF is approximating the characteristics of the Hamming window.
关键词： hyperbolic frequency modulation,matched filter,notch filter,relative sidelobe level,Doppler invariance,Auto-correlation
更新于2025-09-23 15:23:52
-
[IEEE 2018 18th International Symposium on Antenna Technology and Applied Electromagnetics (ANTEM) - Waterloo, ON (2018.8.19-2018.8.22)] 2018 18th International Symposium on Antenna Technology and Applied Electromagnetics (ANTEM) - Excitation of Hyperbolic Plasmons and Transition Radiation in Phosphorene by a Swift Electron
摘要： We analyze the energy loss channels for a fast electron traversing a monolayer phosphorene under oblique incidence taking the retardation effects into account.
关键词： transition radiation,electron energy loss,retardation effects,Phosphorene,hyperbolic plasmon polariton
更新于2025-09-23 15:23:52
-
[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Initial Investigation for the Fabrication of Hyperbolic Metamaterials Based on Ultra-Thin Au Layers
摘要： In this paper, we will present the fabrication possibilities developed within our group for obtaining multilayer hyperbolic metamaterials (HMMs). The minimum metallic layer thickness reproducibly obtainable with our current technology is down to 6 nm, while the dielectric layer can be as low as 4 nm. During the talk we will present our approach for obtaining Au layers with better optical properties than the standard techniques. This is achievable by using an adhesion layer whose influence of the metallic properties is lower than the one of the classical Cr or Ti adhesion layers. These organic adhesion layers behave as dielectrics and thus do not contribute more to the metallic response. Since the imaginary part of permittivity of these layers is negligible and the real part is very close to the silica one, their contribution to the behaviour of the HMMs is minimal. The optical properties of Au with organic adhesion layers showing a closer to theory response than Au with metallic adhesion layer as well as a possible explanation for this behaviour will be presented. This technique can be further used to obtain metal-dielectric multi-layers that lead to HMMs behaviour. Both fabrication possibilities and optical characterisation will be shown and discussed during the talk.
关键词： Au layers optical properties,hyperbolic metamaterials,ultra-thin Au layers
更新于2025-09-23 15:22:29
-
On short-range pulse propagation described by (2 + 1)-dimensional Schr??dinger's hyperbolic equation in nonlinear optical fibers
摘要： The (2 + 1)-dimensional Schr?dinger complex equations are essential physical models that describe the short-range pulse spread in nonlinear media fiber optics. We construct novel complex solutions to Schr?dinger’s complex hyperbolic model by using two different techniques. One method is characterized by the efficient algebraic equations that eventually form. Meanwhile, it uses the dependency variable expressions and its derivatives in the differential equation of the polynomial of a solitary wave. New acquired solutions are rational and exponential solutions expressed by periodic solutions. The solutions are illustrated through 3D- and 2D- plots to clarify the physical features for this model.
关键词： New soliton solutions,Hyperbolic (2 + 1)- dimensional Schr?dinger equation,Complex transformation
更新于2025-09-23 15:21:01
-
Experimental observation of hybrid TE-TM polarized surface waves supported by a hyperbolic metasurface
摘要： Hyperbolic metasurfaces have gained significant attention due to their extraordinary electromagnetic properties to control propagating plane waves, but the excitation and propagation of surface plasmon-polaritons at hyperbolic metasurfaces, called hyperbolic plasmons, have been experimentally observed only recently. However, the advantages of the hyperbolic plasmons, such as hybrid TE-TM polarization discussed below, are not yet fully revealed and analyzed. In this paper, we focus on the numerical and experimental characterization of surface waves in the frequency range from 2 to 8 GHz supported by a hyperbolic metasurface composed of anisotropic metallic Jerusalem crosses printed on a thin dielectric substrate. We show different shapes of equal frequency contours, which correspond to a plethora of excitation and propagation regimes of surface waves. The principal novelty of this work consists in the experimental demonstration of surface waves with hybrid, i.e., mixed TE-TM, polarization. Surface waves with hybrid polarization are a promising tool in a number of applications and phenomena, including polarization converters, plasmonic sensors, plasmon steering over a surface, optical forces, and spin-orbit photonics, and they highlight the impact of on-chip and planar networks.
关键词： hybrid TE-TM polarization,hyperbolic metasurfaces,anisotropic metallic Jerusalem crosses,surface plasmon-polaritons,equal frequency contours
更新于2025-09-23 15:21:01
-
Probing hyperbolic polaritons using infrared attenuated total reflectance micro-spectroscopy
摘要： Hyperbolic polariton modes are highly appealing for a broad range of applications in nanophotonics, including surfaced enhanced sensing, sub-diffractional imaging, and recon?gurable metasurfaces. Here we show that attenuated total re?ectance (ATR) micro-spectroscopy using standard spectroscopic tools can launch hyperbolic polaritons in a Kretschmann–Raether con?guration. We measure multiple hyperbolic and dielectric modes within the naturally hyperbolic material hexagonal boron nitride as a function of different isotopic enrichments and ?ake thickness. This overcomes the technical challenges of measurement approaches based on nanostructuring, or scattering scanning near-?eld optical microscopy. Ultimately, our ATR approach allows us to compare the optical properties of small-scale materials prepared by different techniques systematically.
关键词： Hyperbolic polaritons,infrared attenuated total re?ectance micro-spectroscopy,hexagonal boron nitride,Kretschmann–Raether con?guration
更新于2025-09-23 15:21:01
-
Evaluation of performance of near-field thermophotovoltaic systems based on entropy analysis
摘要： Near-field radiative heat transfer can significantly improve the output power of thermophotovoltaic (TPV) systems. Therefore, it is crucial to explore how to increase the energy conversion efficiencies of near-field TPV systems. In this study, based on the fluctuation–dissipation theorem with the effective medium theory, we evaluate the performance of a near-field TPV system from the formulation of thermodynamics. It is found that a near-field TPV system consisting of InAs or GaSb cell can achieve higher heat flux or efficiency limit, respectively. Moreover, the TPV system with a hyperbolic metamaterial (HMM) emitter composed of nanowire or nanohole arrays can achieve higher heat flux and efficiency limit compared to that of the bulk reference. This is attributable to the HMMs being able to support hyperbolic modes, and the radiation with the HMM emitter exhibits a favorable entropy content for the energy conversion efficiency. This work provides an approach to determine the efficiency limit and establish a target for efficiency of the near-field TPV system without considering how the system works. The results of this study will facilitate the design and application of the HMM emitter and material of the TPV cell to improve the efficiency of near-field TPV systems.
关键词： Thermophotovoltaic systems,Near-field radiative heat transfer,Energy conversion efficiency,Hyperbolic metamaterial,Entropy analysis
更新于2025-09-23 15:19:57
-
[IEEE 2019 Antenna Measurement Techniques Association Symposium (AMTA) - San Diego, CA, USA (2019.10.6-2019.10.11)] 2019 Antenna Measurement Techniques Association Symposium (AMTA) - A Low-Cost Multicopter Based Near-Field Antenna Measurement System Employing Software Defined Radio and 6-D Laser Metrology
摘要： With the purpose of avoiding very fine mesh cells in the proximity of a thin wire, the modified telegrapher’s equations (MTEs) are employed to describe the thin wire voltage and current distributions, which consequently results in reduced number of unknowns and augmented Courant–Friedrichs–Lewy (CFL) number. As hyperbolic systems, both the MTEs and the Maxwell’s equations are solved by the discontinuous Galerkin time-domain (DGTD) method. In realistic situations, the thin wires could be either driven or loaded by circuit networks. The thin wire–circuit interface performs as a boundary condition for the thin wire solver, where the thin wire voltage and current used for the incoming flux evaluation involved in the DGTD-analyzed MTEs are not available. To obtain this voltage and current, an auxiliary current flowing through the thin wire–circuit interface is introduced at each interface. Corresponding auxiliary equations derived from the invariable property of characteristic variable for hyperbolic systems are developed and solved together with the circuit equations established by the modified nodal analysis (MNA) modality. Furthermore, in order to characterize the field and thin wire interactions, a weighted electric field and a volume current density are added into the MTEs and Maxwell–Ampere’s law equation, respectively. To validate the proposed algorithm, three representative examples are presented.
关键词： thin wire–circuit boundary,Characteristic variable,discontinuous Galerkin time-domain (DGTD) method,modified telegrapher’s equation (MTE),hyperbolic system,modified nodal analysis (MNA)
更新于2025-09-23 15:19:57
-
[IEEE 2018 XXIIIrd International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) - Tbilisi (2018.9.24-2018.9.27)] 2018 XXIIIrd International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) - An UWB Antenna Design Having Band-Reject Characteristic by Y-Shaped Strip
摘要： In this study, a new UWB antenna design that shows the band-notched characteristic for UWB application has been designed. To model the antenna, a Hyperbolic-Perforated (HP) method based on two parasitic patches and a parasitic slot (62) is used. As a result, a frequency response is obtained in the band range of 3.1-10.6 GHz for UWB systems. Based on the results, it further refines the core findings, significance of the research, and suggestions for future studies.
关键词： band-notched characteristic,UWB antenna,Hyperbolic-Perforated method,parasitic patches,parasitic slot
更新于2025-09-19 17:15:36
-
Existence Conditions of High-k Modes in Finite Hyperbolic Metamaterials
摘要： The capability to support optical waves with very large wave vectors (high-k) is one of the principle features of hyperbolic metamaterials (HMMs). These waves play the key role in HMM applications such as imaging and lifetime engineering. E?ective medium approximation (EMA) as widely used analytical method to predict HMMs behavior, has shortcomings in calculating high-k modes of practical structures. EMA is applicable to a subwavelength unit cell of implicitly in?nite periodic structures. Using conventional EMA, in the present paper, boundary e?ects and spatial dispersion are taken into consideration to properly compute the high-k modes of ?nite-thickness multilayer HMMs. Applying nonlocal homogenization to stacks of alternating metal-dielectric layers, the corresponding e?ective medium is examined as a high-k waveguide sandwiched between the substrate and an ambient superstrate. The developed theory enables us to recognize two types of bulk waves coined as short-range and long-range propagating modes. Number of such modes as well as their cuto? conditions are quanti?ed for the ?rst time. Validity of the developed theory is veri?ed both numerically by rigorous simulations of the multilayer structures with the transfer matrix method and experimentally by optical characterization of the HMMs in infrared regime.
关键词： subwavelength metal-dielectric multilayers,e?ective medium theory,high-k modes,hyperbolic metamaterials
更新于2025-09-19 17:15:36