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柱矢量光束的紧聚焦在光学微操纵、光学存储、激光微加工、超分辨率成像和粒子加速等领域发挥着重要作用。亚波长光栅平凹透镜对柱矢量光束的紧聚焦的能力仍有提升空间,本文利用闪耀结构将光的能量从零级转移并集中到-1级,对亚波长光栅平凹透镜的聚焦性能进行优化。提高了透镜的衍射效率,增强了焦场的能量。通过调整高斯径向偏振光的形状参数,改变入射光振幅及入射区域半径实现对焦场能量的动态调控。进一步地,调控柱矢量光束的偏振组分能够直接有效地横向调制焦场,获得多样化形貌的焦斑。本文的优化手段对于其他光栅透镜也具有参考意义,该研究结果在超分辨率成像以及光场调控等领域具有潜在的应用价值。 相似文献
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柱矢量光束具有柱对称性的偏振分布,其独特的光场分布和聚焦特性被广泛应用于光学微操纵及光学成像等领域,并迅速向亚波长尺度拓展.通常,亚波长尺度聚焦采用等离激元透镜实现,但存在光场调控的偏振态局限性.而借助光子晶体的负折射效应,不仅能够实现亚波长聚焦或成像,而且应对正交偏振态同时有效.采用对电磁波具有更强调控能力的一维金属光子晶体结构,计算得到的能带结构和等频曲线表明其负折射效应在特定波段对正交偏振态同时有效.在此基础上设计出一维金属光子晶体柱对称平凹镜结构,通过有限元算法模拟显示了可见光波段的径向和旋向偏振光的同时亚波长聚焦行为.进一步的结果表明,改变柱矢量光束的偏振组分能够直接有效地调节焦场空间分布及偏振分布特性.所提出的平凹镜结构能够实现对任意偏振组分的柱矢量光束的亚波长尺度聚焦,且该结构的设计对于各波段情况均有参考意义.该研究结果对小尺度粒子的光学微操纵、超分辨率成像等相关领域具有潜在的应用价值. 相似文献
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亚波长尺寸纵向偏振光束在粒子加速,单个分子偶极矩测量,二次谐波成像和纵向偏振共焦显微镜等方面有非常广泛的应用.本文提出径向调制的Bessel-Gaussian光束模型,经高数值孔径显微物镜聚焦可以获得高纯度的纵向偏振光束.利用矢量衍射理论数值模拟了焦点附近光强分布、磁场分布和能流密度空间分布.结果表明光斑半高全宽度可以达到0.4λ.该方法无需环形孔径或环形相位滤波器,光能利用率高,分辨率好,达到改进各种应用的效果.
关键词:
Bessel-Gaussian光束
纵向偏振光束
聚焦
亚波长 相似文献
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基于波动光学理论,计算了由衍射、球差和色差三者共同作用的电子束斑电流分布,得到了电子束斑的精确信息和电子束曝光机的轴上分辨率。针对某一个具体系统的不同电子束孔径角,以偏转器的位置和相互转角为变量进行了偏转系统的优化设计;综合考虑了电子光学系统的衍射、轴上像差和偏转像差三者与光阑孔径角的不同关系。得到了光柱体的最佳总体性能,保证了电子束曝光机的高分辨率和均匀性。 相似文献
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利用纳米压印结合溅射和反应离子刻蚀工艺制备了周期为1μm、占空比为0.2的亚波长金属光栅,利用紫外-可见-近红外光谱仪测量了光栅的0级反射光谱。在严格耦合波分析的基础上,把光栅区域电磁场的空间谐波通过勒让德多项式展开,使用多项式展开的谱分析法求解常微分方程,计算了该亚波长金属光栅的反射光谱及磁场分布。实验测量结果同矢量衍射理论计算结果都显示,该光栅在近红外、中红外波段具有表面等离子体共振现象。数值计算结果还表明,对于此类亚波长金属光栅,当光栅的深宽比增加时,其反射光谱中会出现更多的反射谷。 相似文献
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近年来,太赫兹科学技术在快速发展,它在毒品、爆炸物、有毒危险品等安全检查及反恐怖方面展现出独特的应用前景。常用的自由空间太赫兹时域光谱技术,尽管具有很多优越性和良好的应用前景,但影响其性能提高和进一步推广应用的一些实际问题仍然存在,如对光斑尺寸和样品体积、质量要求等。近年来,随着亚波长人工结构(包括超材料和表面等离子激元器件)的出现,为该问题的解决提供了新的契机。文章综述了作者在太赫兹亚波长人工结构器件传感应用所开展的一系列研究工作,其中包括薄膜材料传感、不同标号汽油传感以及同位素传感等,显著地提高了被测物质的探测灵敏度,同时降低了对被测物质的体积、质量要求,实现了高灵敏、微量物质传感,为太赫兹安全检查及反恐怖应用提供了技术借鉴。此外,文章还介绍了太赫兹亚波长人工结构传感器件未来的发展前景和面临的挑战。 相似文献
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The comparative analysis of optical properties of aperiodic multilayered systems with equal optical and geometrical thickness of layers has been carried out. The data on the dielectric structures constructed with use of the silver mean principle are represented in more detail. It is established that there is a general quantitative law determining interrelation of scaling in their Fourier spaces and spectral characteristics. It is shown that high sensitivity of aperiodic structures with the same thickness of layers to small changes of refraction indices and the angle of radiation incidence can be of practically using. 相似文献
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Xining Zhao Xiaoping Zhang Pengfei Cao Lin Cheng Jiangxia Duan Libin Cheng Weijie Kong Lili Yang 《Optik》2013,124(24):6740-6742
In this work, beam optical focusing structures capable of double side beam focusing are proposed. The relationships between focal intensity, focal length, focal width and the distance from optical source to lens structure are investigated and numerically simulated. Furthermore, a novel structure that is steadily operating in large wavelength domain is presented, whose properties are well described by comprehensive numerical simulations. 相似文献
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We propose to use diffractive optical element in combination with high NA lens axicon to achieve a high depth of focus when illuminated by a circularly polarized beam. With this kind of system, the focal depth is increased to 12.816λ and the magnetic spot size is reduced to 0.3764λ. However, in the conventional lens with same NA, the FWHM of the magnetic spot is found to be 0.4308λ and its corresponding magnetization depth is only 0.888λ. The author expects that such a high focal depth strong longitudinal magnetic field with large magnetization depth can be widely used in high density magneto optic recording, laser machining, laser cutting and the scanning near-field magnetic microscope. 相似文献
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合金团簇所具备的催化和光学等方面特性与团簇的尺寸、元素组成和元素序列密切关联,因而确定其稳定结构是研究纳米团簇合金性质的首要任务.本文利用基于内核构建的自适应免疫优化算法研究了完整元素组成的CunAum(n+m=61及79)二元合金团簇的稳定结构.应用多体Gupta势函数描述Cu-Au团簇原子间的相互作用.研究结果表明:对于CunAum(n+m=61)团簇,除了当n=12-15时为由三个双二十面体面面相连组成的环状结构外,其余均为二十面体结构.原子总数为79的Cu-Au合金团簇包括堆积缺陷的面心立方结构、双面心立方结构、二十面体、十面体和由四个双二十面体面面相连组成的环状结构.且当Au原子比例高和低时其主要构型分别为二十面体和十面体.此外,还分析了Cu-Au合金团簇结构势能量的分布情况及团簇的相对稳定性.原子分布规律显示Cu原子趋于占据内层,而Au原子趋向于分布在外层. 相似文献
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Structural optimization of Au–Pd bimetallic nanoparticles with improved particle swarm optimization method 下载免费PDF全文
Due to the dependence of the chemical and physical properties of the bimetallic nanoparticles(NPs) on their structures,a fundamental understanding of their structural characteristics is crucial for their syntheses and wide applications. In this article, a systematical atomic-level investigation of Au–Pd bimetallic NPs is conducted by using the improved particle swarm optimization(IPSO) with quantum correction Sutton–Chen potentials(Q-SC) at different Au/Pd ratios and different sizes. In the IPSO, the simulated annealing is introduced into the classical particle swarm optimization(PSO) to improve the effectiveness and reliability. In addition, the influences of initial structure, particle size and composition on structural stability and structural features are also studied. The simulation results reveal that the initial structures have little effects on the stable structures, but influence the converging rate greatly, and the convergence rate of the mixing initial structure is clearly faster than those of the core-shell and phase structures. We find that the Au–Pd NPs prefer the structures with Au-rich in the outer layers while Pd-rich in the inner ones. Especially, when the Au/Pd ratio is 6:4, the structure of the nanoparticle(NP) presents a standardized Pd_(core) Au_(shell) structure. 相似文献
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Broadband acoustic focusing by symmetric Airy beams with phased arrays comprised of different numbers of cavity structures 下载免费PDF全文
We realize broadband acoustic focusing effect by employing two symmetric Airy beams generated from phased arrays,in which the units of the phased arrays consist of different numbers of cavity structures, each of which is composed of a square cavity and two inclined channels in air. The exotic phenomenon arises from the energy overlapping of the two symmetric Airy beams. Besides, we demonstrate the focusing performance with high self-healing property, and discuss the effects of structure parameters on focusing performance, and present the characteristics of the cavity structure with straight channels. Compared with other acoustic lenses, the proposed acoustic lens has advantages of broad bandwidth(about 1.4 kHz), high self-healing property of focusing performance, and free adjustment of focal length. Our finding should have great potential applications in ultrasound imaging and medical diagnosis. 相似文献
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The optimal rendezvous trajectory designs in many current research efforts do not incorporate the practical uncertainties into the closed loop of the design.A robust optimization design method for a nonlinear rendezvous trajectory with uncertainty is proposed in this paper.One performance index related to the variances of the terminal state error is termed the robustness performance index,and a two-objective optimization model(including the minimum characteristic velocity and the minimum robustness performance index)is formulated on the basis of the Lambert algorithm.A multi-objective,non-dominated sorting genetic algorithm is employed to obtain the Pareto optimal solution set.It is shown that the proposed approach can be used to quickly obtain several inherent principles of the rendezvous trajectory by taking practical errors into account.Furthermore,this approach can identify the most preferable design space in which a specific solution for the actual application of the rendezvous control should be chosen. 相似文献
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The oil industry is now increasingly concentrating their efforts and activities in connection with developing fields in deeper
waters, ranging typically from 500 m to 3000 m worldwide. However, the modeling of a full-depth system has become difficult
presently; no tank facility is sufficiently large to perform the testing of a complete FPS with compliant mooring in 1000
m to 3000 m depth, within reasonable limits of model scale. Until recently, the most feasible procedure to meet this challenge
seems to be the so-called “hybrid model testing technique”. To implement this technique, the first and important step is to
design the equivalent water depth truncated mooring system. In this work, the optimization design of the equivalent water
depth truncated mooring system in hybrid model testing for deep sea platforms is investigated. During the research, the similarity
of static characteristics between the truncated and full depth system is mainly considered. The optimization mathematical
model for the equivalent water depth truncated system design is set up by using the similarity in numerical value of the static
characteristics between the truncated system and the full depth one as the objective function. The dynamic characteristic
difference between the truncated and full depth mooring system can be minished by selecting proper design rule. To calculate
the static characteristics of the mooring system, the fourth order Runge-Kutta method is used to solve the static equilibrium
equation of the single mooring line. After the static characteristic of the single mooring line is calculated, the static
characteristic of the whole mooring system is calculated with Lagrange numerical interpolation method. The mooring line material
database is established and the standard material name and the diameter of the mooring line are selected as the primary key.
The improved simulated annealing algorithm for continual & discrete variables and the improved complex algorithm for discrete
variables are employed to perform the optimization calculation. The C++ programming language is used to develop the computer
program according to the object-oriented programming idea. To perform the optimization calculation with the two algorithms
mentioned above respectively and the better result is selected as the final one. To examine the developed program, an example
of equivalent water depth truncated mooring system optimum design calculation on a 100,000-t, turret mooring FPSO in water
depth of 320 m are performed to obtain the conformation parameters of the truncated mooring system, in which the truncated
water depth is 160 m. The model test under some typical environment conditions are performed for both the truncated and the
full depth system with model scale factor λ=80. After comparing the corresponding results from the test of the truncated system with those from the full depth system
test, it’s found that the truncated mooring system design in this work is successful.
Supported by the National Natural Science Foundation of China (Grant Nos. 10602055 and 40776007) and the Natural Science Foundation
of China Jiliang University (Grant No. XZ0501) 相似文献