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[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
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Equivalent-Circuit Model with Retarded Electromagnetic Coupling for Meta-Atoms of Wired Metallic Spheres
摘要： This paper describes the equivalent-circuit model of a metamaterial composed of conducting spheres and wires. This model involves electromagnetic coupling between the conductors, with retardation. The lumped-parameter equivalent circuit, which imports retardation to the electromagnetic coupling, is developed in this paper from Maxwell’s equation. Using the equivalent-circuit model, we clarify the relationship between the retardation and radiation loss; we theoretically demonstrate that the electromagnetic retardation in the near-field represents the radiation loss of the meta-atom in the far-field. Furthermore, this paper focuses on the retarded electromagnetic coupling between two meta-atoms; we estimate the changes in the resonant frequencies and the losses due to the distance between the two coupled meta-atoms. It is established that the dependence characteristics are significantly affected by electromagnetic retardation.
关键词： meta-atom,equivalent-circuit model,metamaterial,electromagnetic coupling,radiation,retardation
更新于2025-09-23 15:22:29
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Microscopic-Stress-Induced Retardation between amorphous silicon nitride and amorphous indium zinc oxide having different stresses
摘要： It is very important to increase the contrast ratio in liquid crystal display (LCD) TV using polymer-stabilized vertical alignment (PS-VA) mode. The luminance of the black state is greatly reduced by changing the parameters of the polarizer, the color filter, and the liquid crystal. However, these have the side effect of reducing the characteristics such as the transmittance, the response time, and the viewing angle. In this paper, the luminance of the black state can be reduced by lowering the stress induced retardation at the edge of pixel electrode without changing the materials in the PS-VA mode. It has been shown for the first time that the stress difference in the heterogeneous layers such as amorphous indium zinc oxide (a-IZO) and amorphous silicon nitride (a-SiNx) can optically create birefringence in the microscopic region. By controlling the stress difference in the heterogeneous membrane, the microscopic-stress-induced retardation (MSIR) could be lowered and the contrast ratio of the PS-VA mode could be increased up to 10%.
关键词： stress,birefringence,polymer-stabilized vertical alignment mode,retardation
更新于2025-09-23 15:22:29
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Theory of two atoms in a chiral waveguide
摘要： A theory is presented that describes the atom and field dynamics for two atoms in a chiral waveguide. A source-field approach is used that enables one to identify the various physical processes contributing to these dynamics. Each atom is prepared in an arbitrary state at t = 0 and the field intensity and correlation functions are calculated, fully accounting for retardation. When the atoms are prepared in identical superposition states, the effects of constructive and destructive interference play a significant role on both the field intensity and second-order correlation function. It is also shown that the results can be taken over to provide a solution for the related problem of a single-photon pulse incident on an atom prepared in an arbitrary initial state.
关键词： chiral waveguide,second-order correlation function,source-field approach,atom-field dynamics,interference,retardation
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Spectroscopic Probing of Retardation Effects in the Casimir-Polder Interaction: A Theoretical Study
摘要： Spectroscopic probing of retardation effects in the Casimir-Polder interaction: a theoretical study. Lennard-Jones theory describes the atom-surface interaction as the instantaneous interaction between a fluctuating dipole and its image predicting a surface induced shift of the atomic energy levels given by -C3/z3, where z is the atom-surface distance and C3 is the van der Waals (vdW) coefficient. In Casimir-Polder theory, demonstrated experimentally with ground state atoms in ~1μm thick metallic cavities [1], atom-surface interactions arise from the modification of vacuum fluctuations next to a dielectric boundary. More recently, Casimir-Polder theory has been tested with ground state cold atoms at intermediate distances from a dielectric surface [2]. Nevertheless, testing the limits of the van der Waals law in the extreme near field remains an important experimental challenge. Additionally, excited state atoms are also of fundamental importance, as their interaction with surfaces can also be of resonant nature. This is of particular interest when atomic dipole transitions couple resonantly to surface polaritons, allowing for exotic near field effects. Selective reflection spectroscopy is a major experimental method testing Casimir-Polder interaction of excited state atoms in the near field. Up to now, experimental results have been interpreted exclusively under the prism of the van der Waals approximation. Here, we show calculations of the fully retarded, spectroscopically relevant, Casimir-Polder potentials for the 6S1/2→6P1/2 and 6S1/2→5D5/2 (Fig.1a) Cs transitions (difference between the Casimir-Polder potentials between probed states) taking into account temperature corrections [3]. The dipole forbidden 6S1/2→6D5/2 transition was recently probed by selective reflection spectroscopy [4]. We demonstrate that accounting for a fully retarded potential leads to significantly different predictions of selective reflection spectra compared to a -C3/z3 vdW approximation. Surprisingly, a vdW model when allowing for an adjustable, ad hoc, van der Waals coefficient can accommodate these differences (Fig1b). However, careful analysis shows that this ad hoc coefficient is not a constant but strongly depends on transition linewidth (collisional broadening) as seen in Fig1c. This is because the contribution of atoms to the experimental spectra depends on their relative detuning, i.e. Casimir-Polder shift divided by the transition linewidth. As the linewidth increases, atoms closer to the surface become more ‘resonant’ with the excitation lasers increasing their contribution [5]. Our analysis shows that by increasing the collisional broadening in selective reflection spectroscopy one can tune the experimental probing depth thus probing atoms that are closer to the surface. This can provide an important experimental tool for measuring the effects of retardation in atom-surface potentials of low lying atomic transitions using selective reflection spectroscopy. Retardation effects can have an impact in atom-metamaterial interactions where plasmons can be tuned in resonance with D1 and D2 lines of alkali atoms at near infrared wavelengths [6].
关键词： van der Waals coefficient,selective reflection spectroscopy,Casimir-Polder interaction,atom-surface interaction,retardation effects
更新于2025-09-16 10:30:52
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Lead Oxalate-Induced Nucleation Retardation for High-Performance Indoor and Outdoor Perovskite Photovoltaics
摘要： Perovskite solar cells have attracted worldwide attention as one of the key research areas in the field of thin film photovoltaics. Although, they exhibit easy solution-processability, it is important to effectively control the crystallization of the light absorbing layer which affects the performance and stability of devices. Here, we present lead oxalate (PbC2O4) as a non-halide lead constituent of the perovskite precursor solution, which contributes to anion replacement during thin film annealing. This strategy limits the perovskite nucleation rate and retards crystallization. As a result, we achieved excellent perovskite film with larger grains and less defects. The open circuit voltage of the optimal device under one sun illumination rose to 1.12 V with a power conversion efficiency (PCE) of 20.20%. In addition, the indoor PCE at 1000 lux can reach 34.86%. This non-halide lead compound dopant provides a guide on the crystallization of perovskite materials and paves a way for the fabrication of non-halide perovskite solar cells.
关键词： PbC2O4,Perovskite solar cells,Nucleation retardation,Non-halide lead dopant
更新于2025-09-12 10:27:22