- 标题
- 摘要
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- 实验方案
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Dynamical behavior of self-accelerating beams in LiNbO3 crystal with background illumination
摘要： We theoretically study the propagations and interactions of an Airy beam, soliton, and nonlinear self-accelerating beam in LiNbO3 crystal modulated by a shorter wavelength background beam. Simulations indicate that the self-accelerating beam and Airy beam can effectively propagate even in self-defocusing media, and the finite-energy Airy beam can generate bright solitons in a self-focusing medium. When two counter-shift Airy beams interact under appropriate conditions, fusion solitons, breathing solitons, and soliton pairs are generated. If we allow a photovoltaic soliton to collide with an Airy beam, X-type waves and soliton deflection occur at a specific phase shift and beam interval. Moreover, we find that the dynamics of two truncated nonlinear self-accelerating beams tend to exhibit straight propagation with attraction and repulsion in the in- and out-of-phase cases, respectively. These results are significant for applications related to optical routing and optical switches.
关键词： optical routing,LiNbO3 crystal,optical switches,Airy beam,nonlinear self-accelerating beam,soliton
更新于2025-09-09 09:28:46
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New photochromic indoline spiropyrans containing cationic substituent in the 2H-chromene moiety
摘要： New indoline spiropyrans containing conjugated cationic fragments and bulky substituents in the 2H-chromene moiety were synthesized by a simple one-pot method. The structures of the obtained compounds were confirmed by 1H and 13C NMR (including 2D methods) and IR spectroscopy, as well as by element analysis and HRMS. Molecular structure of 1,3,3-trimethyl-60-formyl-80-benzyl-spiro[indoline-2,20-2H-chromene] was refined by single crystal X-ray. A comparative analysis of the spectral and photochromic properties of salt spiropyrans and similar structures without a cationic fragment was carried out. It was found that the introduction of the cationic substituent at the 60-position of the 2H-chromene moiety leads to a significant increase in the photoinduced isomer's lifetime.
关键词： Indolines,Molecular switches,2H-chromenes,Photochromism,Single crystal X-ray analysis,Spiropyrans
更新于2025-09-09 09:28:46
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Photoactive Functional Soft Materials (Preparation, Properties, and Applications) || Photochemical Chirality Induction and Inversion in Soft Materials
摘要： Chirality or “handedness” is a prerequisite of the biological world, where life exists in a specific chirality. In living organisms, almost all the sugars are exclusively right‐handed (d‐isomer), amino acids are left‐handed (l‐isomer), and DNA coils assemble into right‐handed helices. The reason behind this homochirality is still an unresolved issue. Inspired by the natural homochirality, the scientific community has been interested in exploring the mechanism of transmission of chirality from the molecular level of monomeric units to the macro‐ or supramolecular level, as well as the origin of chirality. The supramolecular chirality in nature from self‐assembled achiral molecules and its specific handedness play a crucial role in the evolution of life and the development of supramolecular materials. While the chirality of molecules is of configurational and conformational origin, supramolecular level chirality arises from the organization of molecules, with formation of a chiral superstructure by means of long‐range positional and orientational orders of molecules.
关键词： Supramolecular,Polymers,Circularly Polarized Light,Photochromic Switches,Helical Structures,Liquid Crystals,Photochemical,Self-Assembly,Soft Materials,Chirality
更新于2025-09-09 09:28:46
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Reference Module in Materials Science and Materials Engineering || RF MEMS
摘要： RF MEMS switches are quickly becoming very popular with microwave engineers, and they have already been used in antennas, filters, phase shifters, oscillators, multiplexers, and other traditional (radio frequency) RF devices. Their popularity has grown because of their wider bandwidth, better isolation, lower loss at high frequencies, improved linearity, and lower power consumption compared with traditional switch devices.
关键词： filters,antennas,linearity,multiplexers,power consumption,RF MEMS,bandwidth,microwave,switches,isolation,radio frequency,oscillators,phase shifters
更新于2025-09-09 09:28:46
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The effect of the length of terminal n-alkyl carboxylate chain on self-assembling and photosensitive properties of chiral lactic acid derivatives
摘要： A new series of photosensitive azo materials possessing a chiral alkyl lactate moiety and terminal n-alkyl carboxylate unit close to the azo group has been synthesised and studied. The length of the n-alkyl carboxylate chain has been systematically varied in order to establish the effect of the molecular structure on the self-assembling behaviour. Two series of materials possessing hexyl and dodecyl alkyl chains in the chiral part of the molecule have been studied. It has been shown that the length of both the alkyl chains strongly influences the mesomorphic behaviour, however, each chiral/achiral chain has different utility to tune the mesomorphic properties. With exception of the compound with the longest chains, all studied compounds exhibited the chiral tilted ferroelectric smectic C* phase. Based on the combination of terminal alkyl chains, chiral nematic, orthogonal smectic A*, and twist grain boundary smectic A* phases have been detected on cooling beyond the SmC* phase. The presence of the photosensitive functional N=N group in the molecular core allowed further tuning of the material properties by UV light illumination. The E-to-Z photoisomerization of the azo group and subsequent thermal back-isomerisation have been studied in solution by nuclear magnetic resonance and most importantly in the mesophases on bulk samples. We report on UV-induced isothermal switching from chiral smectic and nematic mesophases directly into the isotropic phase, respectively, and differences in the textures of mesophase upon restoration of the ordered liquid.
关键词： E-Z isomerisation,ferroelectric phase,photosensitive liquid crystals,azo group,chiral liquid crystals,NMR spectroscopy,optical switches
更新于2025-09-09 09:28:46
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Enhanced optomechanically induced transparency with magnetic coupling
摘要： Optomechanically induced transparency is a kind of induced transparency arising from the interference of excitation pathways in optomechanical systems and can be used to realize high speed optical switches and precision measurements. Due to the intrinsic feature of optomechanical interaction, optomechanically induced transparency can only be observed under strong pump fields. However, the applications of optomechanically induced transparency in nanophotonics require low pump power and good controllability. Thus it is important to reduce the pump power and improve the controllability of optomechanically induced transparency with current experimental parameters. In this work, we propose a realizable method for the achievement of low-power optomechanically induced transparency by introducing a magnetic force coupling. We show that the magnetic coupling can obviously reduce the pump threshold value, and optomechanically induced transparency with ultralow pump threshold value and desirable controllability can be realized. In comparison to optomechanical system combining piezoelectric materials, the magnetic force-coupled optomechanical system may be a better candidate for optical information process.
关键词： optomechanically induced transparency,low-power,optical switches,precision measurements,magnetic coupling
更新于2025-09-09 09:28:46
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[IEEE 2018 48th European Microwave Conference (EuMC) - Madrid, Spain (2018.9.23-2018.9.27)] 2018 48th European Microwave Conference (EuMC) - Characterization of Phase Change Material Germanium Telluride for RF Switches
摘要： This paper presents the simulation and measured results of a phase-change material (PCM) based radio-frequency (RF) switch optimized to improve the ratio between OFF-state and ON-state resistivity. Various samples having germanium telluride (GeTe) films are developed and imaged using Atomic Force Microscope (AFM) and are compared with cross-wafer resistance measurement results to determine the optimum sputtering conditions of the GeTe films. A simple four-layer fabrication process for GeTe based switches is presented. Several switches with different micro-heater dimensions are compared to investigate the performance of heater and its impact on the isolation performance of switch. A compact RF series switch has been measured, demonstrating an insertion loss of only 0.29 dB and an OFF-state isolation better than 23 dB over DC–26 GHz frequency range, yielding a relatively high Roff/Ron ratio.
关键词： SPST,Latching RF Switches,Phase Change Material (PCM),RF Switch,Germanium Telluride (GeTe)
更新于2025-09-04 15:30:14
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[IEEE 2018 48th European Microwave Conference (EuMC) - Madrid, Spain (2018.9.23-2018.9.27)] 2018 48th European Microwave Conference (EuMC) - Double-Port Double-Throw (DPDT) Switch Matrix Based on Phase Change Material (PCM)
摘要： This paper presents the design, fabrication and high frequency characterization of GeTe phase change material based double port double throw switch (DPDT) matrix using phase change materials. The material exhibits non-volatile conductivity changes between amorphous high resistance and crystalline low resistance state. Being non-volatile, these RF switches do not require permanent bias to be maintained in a given state. We present the design of 4-terminal RF switch and the integration of this structure into wideband DPDT matrices. The proposed device has less than 2 dB loss and more than 20 dB below 5 GHz. This matrix can retain its state without any applied bias.
关键词： Phase change material,routing circuits,bi-stable RF switches,GeTe
更新于2025-09-04 15:30:14
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[IEEE 2018 48th European Microwave Conference (EuMC) - Madrid, Spain (2018.9.23-2018.9.27)] 2018 48th European Microwave Conference (EuMC) - A Fully Printed Switch Based on VO<inf>2</inf> Ink for Reconfigurable RF Components
摘要： Recently, vanadium dioxide (VO2) has emerged as an attractive phase change material which can be used for reconfigurable or switchable RF components. However, at present, VO2 is deposited by expensive and complex thin film micro-fabrication techniques. With the surge in low cost, additively manufactured or printed components, it will be beneficial to print phase change materials or switches as well. The issue is there are no such functional inks available in the market. In this work, we present, for the first time VO2 based ink that changes its conductive properties based on temperature. Precisely, it displays insulating properties at room temperature (resistance of ~5KΩ in the off-state), but becomes conductive when heated around 70°C (resistance of ~10Ω in the on-state). Based on this VO2 ink and a custom silver-organo-complex (SOC) ink, we demonstrate a fully printed thermally controlled RF switch in this work. In a CPW based shunt configuration, the fully printed switch provides more than 15 dBs of isolation (in the off state) and a 0.5-2 dB of insertion loss (in the on state) from 100 MHz to 30 GHz frequency band. To demonstrate its application, a fully printed frequency reconfigurable planar inverted F antenna (PIFA) has also been demonstrated in this work.
关键词： Vanadium dioxide,CPW line,RF switches,phase change,printing,reconfigurability
更新于2025-09-04 15:30:14
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Ultrafast defect dynamics: A new approach to all optical broadband switching employing amorphous selenium thin films
摘要： Optical switches offer higher switching speeds than electronics, however, in most cases utilizing the interband transitions of the active medium for switching. As a result, the signal suffers heavy losses. In this article, we demonstrate a simple and yet efficient ultrafast broadband all-optical switching on ps timescale in the sub-bandgap region of the a-Se thin film, where the intrinsic absorption is very weak. The optical switching is attributed to short-lived transient defects that form localized states in the bandgap and possess a large electron-phonon coupling. We model these processes through first principles simulation that are in agreement with the experiments.
关键词： electron-phonon coupling,optical switches,interband transitions,all optical broadband switching,first principles simulation,amorphous selenium thin films,ultrafast defect dynamics,sub-bandgap region,transient defects
更新于2025-09-04 15:30:14