Vector vortex beams(VVBs) have attracted significant attention in both classical and quantum optics. Liquid crystal(LC),beyond its applications in information display, has emerged as a versatile tool for manipulating ...Vector vortex beams(VVBs) have attracted significant attention in both classical and quantum optics. Liquid crystal(LC),beyond its applications in information display, has emerged as a versatile tool for manipulating VVBs. In this review, we focus on the functions and applications of typical LC devices in recent studies on controlling the space-variant polarized vortex light. Manipulation of VVBs through patterned nematic LC optical elements, patterned cholesteric LC optical elements, self-assembled defects, and LC spatial light modulators is discussed separately. Moreover, LC-based novel optical applications in the field of quantum information are reviewed.展开更多
提出并研究了一种基于拓扑优化设计的太赫兹薄液晶(LC)编码超表面。基于遗传算法对金属谐振图案进行拓扑优化,设计了一种薄厚度反射型2 bit LC编码超表面单元,LC层厚度仅为14μm,克服了利用多层LC或LC谐振切换机制实现多比特编码外部馈...提出并研究了一种基于拓扑优化设计的太赫兹薄液晶(LC)编码超表面。基于遗传算法对金属谐振图案进行拓扑优化,设计了一种薄厚度反射型2 bit LC编码超表面单元,LC层厚度仅为14μm,克服了利用多层LC或LC谐振切换机制实现多比特编码外部馈电系统复杂的缺点,同时具有较快的响应速率。基于设计的LC 2 bit编码超表面单元,利用遗传算法对阵列编码排布进行逆向设计,增强波束调控的主动性和灵活性,仿真实现了0.394 THz处波束赋形和涡旋波束的功能。结果表明:对于波束赋形,该超表面单元不仅可以实现俯仰角在0°~30°范围内、方位角在0°~360°范围内任意角度的单波束和多波束的调控,还可以对多波束的各个目标波束进行独立调控,同时扫描和跟踪多个目标,实现对太赫兹波束更优性能的调控;对于涡旋波束,该超表面单元可以产生拓扑荷数l=±1、±2、±3且模式纯度大于70%的涡旋波束,同时可实现俯仰角在0°~30°范围内、方位角在0°~360°范围内任意角度的单涡旋和多涡旋波束的灵活调控。展开更多
The dynamic characteristics of a quartz crystal resonator（QCR） in thicknessshear modes（TSM） with the upper surface covered by an array of micro-beams immersed in liquid are studied. The liquid is assumed to be inv...The dynamic characteristics of a quartz crystal resonator（QCR） in thicknessshear modes（TSM） with the upper surface covered by an array of micro-beams immersed in liquid are studied. The liquid is assumed to be inviscid and incompressible for simplicity. Dynamic equations of the coupled system are established. The added mass effect of liquid on micro-beams is discussed in detail. Characteristics of frequency shift are clarified for different liquid depths. Modal analysis shows that a drag effect of liquid has resulted in the change of phase of interaction（surface shear force）, thus changing the system resonant frequency. The obtained results are useful in resonator design and applications.展开更多
Smart beams play a vital role in modern intelligent vehicles and have recently attracted significant attention.A spatial light modulator with high optical efficiency,low cost,and compact size is crucial for designing ...Smart beams play a vital role in modern intelligent vehicles and have recently attracted significant attention.A spatial light modulator with high optical efficiency,low cost,and compact size is crucial for designing smart beams.Here,we mix cholesteric liquid crystals with dichroic black dye and a monomer.After UV polymerization,the sample exhibits a low driving voltage of 26 V,a high transmittance of over 70%,and an On-off ratio over 280,thanks to the joint contribution of both the absorption and the scattering effect.A smart beam device is demonstrated by electrically addressing the dye-doped and polymer-stabilized cholesteric liquid crystal with pixelated electrodes.Light patterns with arbitrary designs are projected dynamically.The switching time reaches several tens of milliseconds.This strategy brings new designs to intelligent vehicles and may also inspire applications in public information displays,advertising,and even AR/VR displays.展开更多
In this Letter, we propose that the photopatterned liquid crystal(LC) can act as a broadband and efficient terahertz(THz) Bessel vortex beam(BVB) generator. The mechanism lies in the frequency-independent geometric ph...In this Letter, we propose that the photopatterned liquid crystal(LC) can act as a broadband and efficient terahertz(THz) Bessel vortex beam(BVB) generator. The mechanism lies in the frequency-independent geometric phase modulation induced by the spatially variant LC directors. By adopting large birefringence LCs and optimizing the cell gap, the maximized mode conversion efficiency can be continuously adjusted in broadband.Furthermore, the LC patterns can be designed and fabricated at will, which enables the THz BVBs to carry various topological charges. Such a THz LC BVB generator may facilitate the advanced THz imaging and communication apparatus.展开更多
In this paper,we propose an effective method to compensate for the performance degradation of optically addressed spatial light modulators(OASLMs).The thermal deposition problem usually leads to the on-off ratio reduc...In this paper,we propose an effective method to compensate for the performance degradation of optically addressed spatial light modulators(OASLMs).The thermal deposition problem usually leads to the on-off ratio reduction of amplitude OASLM,so it is difficult to achieve better results in high-power laser systems.Through the analysis of the laser-induced temperature rise model and the liquid crystal layer voltage model,it is found that reducing the driving voltage of the liquid crystal light valve and increasing the driving current of the optical writing module can compensate for the decrease of on-off ratio caused by temperature rise.This is the result of effectively utilizing the photoconductive effect of Bi_(12)SiO_(20)(BSO)crystal.The experimental results verify the feasibility of the proposed method and increase the laser withstand power of amplitude-only OASLM by about a factor of 2.5.展开更多
To meet the application need for agile precision beam steering, a novel liquid crystal prism device with a simple structure, convenient control, low cost and applicable performance is presented, and analysed theoretic...To meet the application need for agile precision beam steering, a novel liquid crystal prism device with a simple structure, convenient control, low cost and applicable performance is presented, and analysed theoretically and experimentally. The relationships between the optical path and the thickness of the liquid crystal cell under different voltages are investigated quantitatively by using a theoretical model. Analysis results show that the optical path profile of the liquid crystal prism has a quasi-linear slope and the standard deviation of the linear slope is less than 16 nm. The slope ratio can be changed by a voltage, which achieves the programmable beam steering and control. Practical liquid crystal prism devices are fabricated. Their deflection angles and wavefront profiles with different voltages are experimentally tested. The results are in good agreement with the simulated results. The results imply that the agile beam steering in a scope of 100μrad with a micro-rad resolution is substantiated in the device. The two-dimensional beam steering is also achieved by cascading two liquid crystal prism devices.展开更多
Studying liquid phase nanoscale dynamic processes of oxide nanoparticles is of considerable interest to a wide variety of fields.Recently developed liquid phase transmission electron microscopy(LP-TEM)is a promising t...Studying liquid phase nanoscale dynamic processes of oxide nanoparticles is of considerable interest to a wide variety of fields.Recently developed liquid phase transmission electron microscopy(LP-TEM)is a promising technique,but destabilization of oxides by solid-liquid?electron interactions remains an important challenge.In this work we present a methodology to assess LP-TEM oxide stability in an aqueous phase,by subjecti ng several oxides of tech no logical importa nee to a controlled electr on dose in water.We show a correlati on based on the Gibbs free en ergy of oxide hydrati on that can be used to assess the stability of oxides and dem on strate the existenee of several remarkably stable oxides,with no observable structural changes after one hour of electron beam irradiation in LP-TEM.Rationalizing such destabilization phenomena combined with the identification of stable oxides allows for designing LP-TEM experiments free from adverse beam effects and thus in vestigati ons of numerous releva ntnano scale processes in water.展开更多
Air or inert atmosphere irradiation of liquid normal alkanes C5-C8 and benzene by electron beam was carried out. Oxidation （in the air） or isomerization （in the inert gases） of liquid normal alkanes under electron...Air or inert atmosphere irradiation of liquid normal alkanes C5-C8 and benzene by electron beam was carried out. Oxidation （in the air） or isomerization （in the inert gases） of liquid normal alkanes under electron beam was shown. Action of electron beam on benzene molecules in the air or in the inert atmosphere leads to biphenyl, terphenyl and polymers. Irradiation by the bunch of electrons of mixture hexane with 10% benzene reduced to firm fractions （fullerene＇s similar structures） in a deposit.展开更多
基金This work was supported by the National Key Research and Development Program of China(Nos.2017YFA0303700 and 2019YFA0308700)the National Natural Science Foundation of China(NSFC)(Nos.11874212,11890704,62035008,12004175,and 62175101)the Natural Science Foundation of Jiangsu Province(No.BK20200311)。
文摘Vector vortex beams(VVBs) have attracted significant attention in both classical and quantum optics. Liquid crystal(LC),beyond its applications in information display, has emerged as a versatile tool for manipulating VVBs. In this review, we focus on the functions and applications of typical LC devices in recent studies on controlling the space-variant polarized vortex light. Manipulation of VVBs through patterned nematic LC optical elements, patterned cholesteric LC optical elements, self-assembled defects, and LC spatial light modulators is discussed separately. Moreover, LC-based novel optical applications in the field of quantum information are reviewed.
基金Project supported by the National Natural Science Foundation of China(Nos.11272127 and51425006)the Research Fund for the Doctoral Program of Higher Education of China(No.20130142110022)the Grant from the Impact and Safety of Coastal Engineering Initiative Program of Zhejiang Provincial Government at Ningbo University(No.zj1213)
文摘The dynamic characteristics of a quartz crystal resonator（QCR） in thicknessshear modes（TSM） with the upper surface covered by an array of micro-beams immersed in liquid are studied. The liquid is assumed to be inviscid and incompressible for simplicity. Dynamic equations of the coupled system are established. The added mass effect of liquid on micro-beams is discussed in detail. Characteristics of frequency shift are clarified for different liquid depths. Modal analysis shows that a drag effect of liquid has resulted in the change of phase of interaction（surface shear force）, thus changing the system resonant frequency. The obtained results are useful in resonator design and applications.
基金This work was supported by the National Key Research and Development Program of China(No.2022YFA1203703)the National Natural Science Foundation of China(NSFC)(No.62035008)the Fundamental Research Funds for the Central Universities(No.021314380233).
文摘Smart beams play a vital role in modern intelligent vehicles and have recently attracted significant attention.A spatial light modulator with high optical efficiency,low cost,and compact size is crucial for designing smart beams.Here,we mix cholesteric liquid crystals with dichroic black dye and a monomer.After UV polymerization,the sample exhibits a low driving voltage of 26 V,a high transmittance of over 70%,and an On-off ratio over 280,thanks to the joint contribution of both the absorption and the scattering effect.A smart beam device is demonstrated by electrically addressing the dye-doped and polymer-stabilized cholesteric liquid crystal with pixelated electrodes.Light patterns with arbitrary designs are projected dynamically.The switching time reaches several tens of milliseconds.This strategy brings new designs to intelligent vehicles and may also inspire applications in public information displays,advertising,and even AR/VR displays.
基金supported by the National Natural Science Foundation of China (NSFC)(No. 61922038)the Fundamental Research Funds for the Central Universities (No. 14380170)。
文摘In this Letter, we propose that the photopatterned liquid crystal(LC) can act as a broadband and efficient terahertz(THz) Bessel vortex beam(BVB) generator. The mechanism lies in the frequency-independent geometric phase modulation induced by the spatially variant LC directors. By adopting large birefringence LCs and optimizing the cell gap, the maximized mode conversion efficiency can be continuously adjusted in broadband.Furthermore, the LC patterns can be designed and fabricated at will, which enables the THz BVBs to carry various topological charges. Such a THz LC BVB generator may facilitate the advanced THz imaging and communication apparatus.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA25020303)the financial support of the Self Deployed Projects of Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences.
文摘In this paper,we propose an effective method to compensate for the performance degradation of optically addressed spatial light modulators(OASLMs).The thermal deposition problem usually leads to the on-off ratio reduction of amplitude OASLM,so it is difficult to achieve better results in high-power laser systems.Through the analysis of the laser-induced temperature rise model and the liquid crystal layer voltage model,it is found that reducing the driving voltage of the liquid crystal light valve and increasing the driving current of the optical writing module can compensate for the decrease of on-off ratio caused by temperature rise.This is the result of effectively utilizing the photoconductive effect of Bi_(12)SiO_(20)(BSO)crystal.The experimental results verify the feasibility of the proposed method and increase the laser withstand power of amplitude-only OASLM by about a factor of 2.5.
基金supported by the National High Technology Research and Development Program of China(Grant No.2009AA8042017)the Postdoctoral Science Foundation of University of Electronic Science and Technology of China
文摘To meet the application need for agile precision beam steering, a novel liquid crystal prism device with a simple structure, convenient control, low cost and applicable performance is presented, and analysed theoretically and experimentally. The relationships between the optical path and the thickness of the liquid crystal cell under different voltages are investigated quantitatively by using a theoretical model. Analysis results show that the optical path profile of the liquid crystal prism has a quasi-linear slope and the standard deviation of the linear slope is less than 16 nm. The slope ratio can be changed by a voltage, which achieves the programmable beam steering and control. Practical liquid crystal prism devices are fabricated. Their deflection angles and wavefront profiles with different voltages are experimentally tested. The results are in good agreement with the simulated results. The results imply that the agile beam steering in a scope of 100μrad with a micro-rad resolution is substantiated in the device. The two-dimensional beam steering is also achieved by cascading two liquid crystal prism devices.
文摘Studying liquid phase nanoscale dynamic processes of oxide nanoparticles is of considerable interest to a wide variety of fields.Recently developed liquid phase transmission electron microscopy(LP-TEM)is a promising technique,but destabilization of oxides by solid-liquid?electron interactions remains an important challenge.In this work we present a methodology to assess LP-TEM oxide stability in an aqueous phase,by subjecti ng several oxides of tech no logical importa nee to a controlled electr on dose in water.We show a correlati on based on the Gibbs free en ergy of oxide hydrati on that can be used to assess the stability of oxides and dem on strate the existenee of several remarkably stable oxides,with no observable structural changes after one hour of electron beam irradiation in LP-TEM.Rationalizing such destabilization phenomena combined with the identification of stable oxides allows for designing LP-TEM experiments free from adverse beam effects and thus in vestigati ons of numerous releva ntnano scale processes in water.
文摘Air or inert atmosphere irradiation of liquid normal alkanes C5-C8 and benzene by electron beam was carried out. Oxidation （in the air） or isomerization （in the inert gases） of liquid normal alkanes under electron beam was shown. Action of electron beam on benzene molecules in the air or in the inert atmosphere leads to biphenyl, terphenyl and polymers. Irradiation by the bunch of electrons of mixture hexane with 10% benzene reduced to firm fractions （fullerene＇s similar structures） in a deposit.
