- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Coherent control of spatial and angular Goos-H?¤nchen shifts in a metal-clad waveguide structure
摘要： A metal-clad waveguide backed by a coherent atomic medium is proposed to achieve tunable giant spatial and angular Goos-H?nchen (GH) shifts. With a metal layer of appropriate thickness, a large GH shift can occur simultaneously for transverse-magnetic- and transverse-electric-polarized light beams when the waveguide modes are resonantly excited. The phase change and dip slope of the re?ection coef?cient around the resonance angle are closely related to the system’s internal damping, which depends on the absorption of the medium. Then based on the quantum coherence effect, the spatial and angular shifts can be greatly enhanced by adjusting the parameters of the atomic system. The lateral displacement can also be switched from positive to negative or vice versa via coherent control of the absorption by the medium. Moreover, the dependence of the resonance angle of the guided mode on the refractive index makes the peak position of GH shifts tunable. The proposed scheme provides more ?exibility for manipulating the spatial and the angular GH shifts, and it has potential applications in optical switches, beam steering, etc.
关键词： optical switches,coherent atomic medium,quantum coherence effect,beam steering,Goos-H?nchen shifts,metal-clad waveguide
更新于2025-09-23 15:21:01
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Parameters extraction of photovoltaic models using triple-phase teaching-learning-based optimization
摘要： Hybrid analog/digital multiple-input multiple-output architectures were recently proposed as an alternative for fully digital-precoding in millimeter wave wireless communication systems. This is motivated by the possible reduction in the number of RF chains and analog-to-digital converters. In these architectures, the analog processing network is usually based on variable phase shifters. In this paper, we propose hybrid architectures based on switching networks to reduce the complexity and the power consumption of the structures based on phase shifters. We define a power consumption model and use it to evaluate the energy efficiency of both structures. To estimate the complete MIMO channel, we propose an open-loop compressive channel estimation technique that is independent of the hardware used in the analog processing stage. We analyze the performance of the new estimation algorithm for hybrid architectures based on phase shifters and switches. Using the estimate, we develop two algorithms for the design of the hybrid combiner based on switches and analyze the achieved spectral efficiency. Finally, we study the tradeoffs between power consumption, hardware complexity, and spectral efficiency for hybrid architectures based on phase shifting networks and switching networks. Numerical results show that architectures based on switches obtain equal or better channel estimation performance to that obtained using phase shifters, while reducing hardware complexity and power consumption. For equal power consumption, all the hybrid architectures provide similar spectral efficiencies.
关键词： switches,precoding,Millimeter wave,hybrid architecture,channel estimation
更新于2025-09-23 15:21:01
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Central-to-Helical-to-Axial-to-Central Transfer of Chirality with a Photoresponsive Catalyst
摘要： Recent advances in molecular design have displayed striking examples of dynamic chirality transfer between various elements of chirality, e.g. from central to either helical or axial chirality and vice versa. While considerable progress in atroposelective synthesis has been made, it is intriguing to design chiral molecular switches able to provide selective and dynamic control of axial chirality with an external stimulus to modulate stereochemical functions. Here, we report the synthesis and characterization of a photoresponsive bis(2-phenol)-substituted molecular switch 1. The unique design exhibits a dynamic hybrid central-helical-axial transfer of chirality. The change of preferential axial chirality in the biaryl motif is coupled to the reversible switching of helicity of the overcrowded alkene core, dictated by the fixed stereogenic center. The potential for dynamic control of axial chirality was demonstrated by using (R)-1 as switchable catalyst to direct the stereochemical outcome of the catalytic enantioselective addition of diethylzinc to aromatic aldehydes, with successful reversal of enantioselectivity for several substrates.
关键词： atropisomers,photoresponsive catalyst,chirality transfer,photoisomerization,dynamic selectivity control,molecular switches
更新于2025-09-23 15:21:01
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[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) - Optimal Switching Operation of PT-Symmetric Dimmers with Nonuniform Gain/Loss and Coupling Profiles
摘要： We assess through a variational optimization approach the optimal gain-loss profile for a non-uniform PT-symmetric coupler allowing the realization of a binary transfer function and minimizing the deviation of the total traveling light intensity as compared to that holding in a conservative system. We bring evidence that the gain-loss profile fulfilling this requirement corresponds to a non-conventional situation when light intensity is conserved in every point along the propagation distance in the PT-symmetric system. Furthermore, the optimal profile thus found corresponds to a practically important case of optical switching operation achieved with a minimal amount of amplification level. We show that switching architectures using such type of gain-loss profiles are very substantially advantageous as compared to conventional uniform PT-symmetric couplers. Furthermore, this type of optimal profile turns out to be robust with respect to fabrication imperfections. This opens new prospects for functional applications of PT-symmetric devices in photonics.
关键词： variational and optimization methods,parity-time symmetry,optical switches,waveguides and couplers
更新于2025-09-23 15:21:01
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Redox-Switchable Cyan Fluorescence of a BODIPY Analog Inspired by Propentdyopent Pigments
摘要： The combination of reversible redox chemistry and bright redox-responsive emission properties is key to the development of electrofluorochromic switches for applications in bioimaging and optoelectronics. Herein, the redox-active dipyrrin-1,9-dione fragment, which is characteristic of the propentdyopent family of heme metabolites and urinary pigments, is employed for the synthesis of a BODIPY analog. This boron difluoride complex exhibits bright fluorescence in organic solvents and a significant ipsochromic shift to the cyan region when compared to typical green BODIPY dyes. Electrochemical and spectroscopic measurements show that the dipyrrindione ligand acts as an electron reservoir by hosting an unpaired spin upon one-electron reduction. This ligand-based redox event reversibly abolishes the fluorescence emission, thus switching off the novel electrofluorochromic system.
关键词： Redox chemistry,Switches,BODIPY,Fluorescence,Dyes/Pigments
更新于2025-09-23 15:21:01
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Nanoplasma-enabled picosecond switches for ultrafast electronics
摘要： The broad applications of ultrawide-band signals and terahertz waves in quantum measurements, imaging and sensing techniques, advanced biological treatments, and very-high-data-rate communications have drawn extensive attention to ultrafast electronics. In such applications, high-speed operation of electronic switches is challenging, especially when high-amplitude output signals are required. For instance, although field-effect and bipolar junction devices have good controllability and robust performance, their relatively large output capacitance with respect to their ON-state current substantially limits their switching speed. Here we demonstrate a novel on-chip, all-electronic device based on a nanoscale plasma (nanoplasma) that enables picosecond switching of electric signals with a wide range of power levels. The very high electric field in the small volume of the nanoplasma leads to ultrafast electron transfer, resulting in extremely short time responses. We achieved an ultrafast switching speed, higher than 10 volts per picosecond, which is about two orders of magnitude larger than that of field-effect transistors and more than ten times faster than that of conventional electronic switches. We measured extremely short rise times down to five picoseconds, which were limited by the employed measurement set-up. By integrating these devices with dipole antennas, high-power terahertz signals with a power–frequency trade-off of 600 milliwatts terahertz squared were emitted, much greater than that achieved by the state of the art in compact solid-state electronics. The ease of integration and the compactness of the nanoplasma switches could enable their implementation in several fields, such as imaging, sensing, communications and biomedical applications.
关键词： picosecond switches,terahertz waves,ultrafast electronics,nanoplasma,electronic switches
更新于2025-09-23 15:19:57
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Encyclopedia of Automotive Engineering || Body and Lighting ECU (Key-less Entry, Sonar, HID, LED Usage for Lamps)
摘要： The purpose of body controls is to improve aspects of vehicle performance, such as comfort, usability, safety, theft prevention, serviceability, and the like. This is accomplished by controlling the output of motors, lamps, and the like, based on inputs mainly from switches and sensors. Table 1 lists some examples of products and functions that aim to improve these aspects of performance. Many of these body control products are designed to enhance the perceived value of the vehicle and to create an appealing impression to the user. For this reason, these controls were conventionally installed mainly in luxury vehicles. In recent years, however, technological innovations have reduced costs to the level where more and more have become available in mass-market vehicles.
关键词： Body controls,switches,safety,theft prevention,usability,vehicle performance,comfort,sensors,serviceability,lamps,motors
更新于2025-09-23 15:19:57
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Double Fano resonances in hybrid disk/rod artificial plasmonic molecules based on dipole-quadrupole coupling
摘要： Fano resonance can be achieved by the destructive interference between a superradiant bright mode and a subradiant dark mode. A variety of artificial plasmonic oligomers have been fabricated to generate Fano resonance for its extensive applications. However, the Fano resonance in plasmonic oligomer systems comes from the interaction of all metal particles, which greatly limits the tunability of the Fano resonance. Besides, only a single Fano resonance is supported by many existing plasmonic oligomers, while multiple Fano resonances mostly occur in complex and multilayer structures, whose fabrication is greatly challenging. Here, a simple asymmetric plasmonic molecule consisting of a central metal disk and two side-coupled parallel metal rods is demonstrated. The simulation and experimental results clearly show that double Fano resonances appear in the transmission spectrum. In addition, the two Fano peaks can be independently tuned and single/double Fano peak switching can be achieved by changing one rod length or the gap distances between the rods and the disk. The modulation method is simple and effective, which greatly increases the tunability of the structure. The proposed asymmetric artificial plasmonic molecule can have applications in multi-channel optical switches, filters and biosensors. Moreover, the controllable plasmonic field intensity in the gap between the disk and rods also provides a new control means for plasmon-induced photocatalytic reactions and biosynthesis.
关键词： plasmonic oligomers,biosynthesis,Fano resonance,filters,optical switches,biosensors,asymmetric plasmonic molecule,plasmon-induced photocatalytic reactions,double Fano resonances
更新于2025-09-23 15:19:57
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Nonadiabatic Dynamics in a Laser Field: Using Floquet Fewest Switches Surface Hopping To Calculate Electronic Populations for Slow Nuclear Velocities
摘要： We investigate two well-known approaches for extending the fewest switches surface hopping (FSSH) algorithm to periodic time-dependent couplings. The first formalism acts as if the instantaneous adiabatic electronic states were standard adiabatic states, which just happen to evolve in time. The second formalism replaces the role of the usual adiabatic states by the time-independent adiabatic Floquet states. For a set of modified Tully model problems, the Floquet FSSH (F-FSSH) formalism gives a better estimate for both transmission and reflection probabilities than the instantaneous adiabatic FSSH (IA-FSSH) formalism, especially for slow nuclear velocities. More importantly, only F-FSSH predicts the correct final scattering momentum. Finally, in order to use Floquet theory accurately, we find that it is crucial to account for the interference between wavepackets on different Floquet states. Our results should be of interest to all those interested in laser-induced molecular dynamics.
关键词： Electronic Populations,Nonadiabatic Dynamics,Floquet Fewest Switches Surface Hopping,Slow Nuclear Velocities,Laser Field
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS) - Macau, China (2019.11.3-2019.11.8)] 2019 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS) - Robust UAV Position and Attitude Estimation using Multiple GNSS Receivers for Laser-based 3D Mapping
摘要： We demonstrate error-free 100-Gb/s optical packet switching with low power consumption by using a combination of a label processor and 8 × 8 broadcast-and-select (B&S) optical switch. To achieve energy-ef?cient label processing, an optical-trigger-pulse generator that consumes energy only for a very short duration is realized, whereas the optoelectronic serial-to-parallel converter used to interface the fast label bits to a slow CMOS processor has been improved to operate with a reduced trigger pulse energy of 0.35 pJ. Moreover, the electro-absorption-modulator-based B&S optical switch is signi?cantly enhanced by introducing a surface ground electrode for eliminating electrical crosstalk and integrated spot-size converters with easy fabrication process. The total power consumption of the full 8 × 8 optical packet switch is estimated to be as low as 27.3 W or 3.4 W/100-Gb/s port.
关键词： optical switches,Data center network,optical label processor,optical packet switching (OPS),optical circuit switching (OCS)
更新于2025-09-23 15:19:57