共查询到20条相似文献,搜索用时 31 毫秒
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C. N. Alexeyev E. V. Barshak D. V. Vikulin B. P. Lapin M. A. Yavorsky 《Optics and Spectroscopy》2018,124(4):560-566
Analytical expressions for higher-order modes with azimuthal number |?|≥ 2and their propagation constants for multielliptical optical fibers exhibiting a torsional mechanical stress are obtained in the vicinity of the resonance twist-pitch values. It is demonstrated that the resonance modes represent a superposition of two optical vortices with identical circular polarization and opposite signs of the topological charge. The effect of topological-charge inversion of the output optical vortex controlled by a change of sign of the circular polarization of the input beam is predicted. This effect paves the way to creating a logical CNOT element based on multielliptical fibers. 相似文献
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We report the generation of a crossed, focused, optical vortex beam by using a pair of hybrid holograms, which combine the vortex phase and lens phase onto a spatial light modulator. We study the intensity distributions of the vortex beam in free propagation space, and the relationship of its dark spot size with the incident Gaussian beam's waist, the lens's focal length, and its orbital angular momentum. Our results show that the crossed, focused, vortex beam's dark spot size can be as small as 16.3μm and adjustable by the quantum number of the orbital angular momentum, and can be used to increase the density of trapped molecules. Furthermore, we calculate the optical potential of the blue-detuned, crossed vortex beam for MgF molecules. It is applicable to cool and trap neutral molecules by intensity-gradient-induced Sisyphus cooling, as the intensity gradient of such vortex beam is extremely high near the focal point. 相似文献
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The Fraunhofer diffraction pattern of a vortex beam by an annular triangle aperture is analyzed theoretically and experimentally. It is found that the pattern of the far-field diffraction intensity distribution exhibits a triangular lattice array, which becomes much clearer with the increase of the ratio of the inner to the outer side of the annular triangle aperture. The number of spot points of any external side of the triangular lattice array minus one is just equal to the topological charge value of the measured optical vortex. For the vortex beam with negative topological charge, the triangular diffraction pattern after the annular triangle aperture will be rotated by 180° in relation to the case of the positive topological charge. Based on the above properties, we propose a simple and feasible method to determine the magnitude and sign of the topological charge of an optical vortex beam. 相似文献
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Vijay KumarV.V.G. Krishna Inavalli Nirmal K. Viswanathan 《Optics Communications》2012,285(24):4866-4873
We present here controlled generation of asymmetric optical vector-vortex beams using a two-mode optical fiber and study the dynamic evolution of the transverse energy flow (TEF) when focused through a spherical lens. The dependence of the TEF on various factors such as the vortex charge, vortex anisotropy and polarization structure around the vortex core is explored. It is found that the TEF is directly proportional to the phase gradient and its direction is governed by the vortex charge. The presence of C-point polarization singularity in the beam and the polarization structure around it results in vibrational phase gradient which is the major factor deciding the TEF in vector-vortex beams. 相似文献
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The focus-shaping technique of a cylindrically polarized vortex beam by a high numerical-aperture lens is reported. Such a polarized vortex beam is decomposed into radial and azimuthal polarization. It is shown that the total intensity distribution in the focal region is dependent not only on the numerical-aperture maximal angle and the polarization rotation angle but also on the topological charge. By choosing the proper combination of parameters, the adjustably confined flat-topped focus and focal hole can be obtained. The focus-shaping technique may find wide applications, such as optical tweezers, laser printing and material processing. 相似文献
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We demonstrate, analytically and experimentally, a simple, but effective method to determine the topological charge of an optical vortex by using a spherical bi-convex lens, a ubiquitous optical element found in any optics laboratory. Just by tilting the lens and recording the intensity distribution of a propagating vortex at a predicted position past the lens, we have been able to measure both the sign and the magnitude of the topological charge m up to m=±14. Our experimental results are in excellent agreement with analytical predictions. 相似文献
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The theoretical and experimental results of tightly focused radially polarized vortex beams are demonstrated. An auto-focus technology is introduced into the measurement system in order to enhance the measurement precision, and the radially polarized vortex beams are generated by a liquid-crystal polarization converter and a vortex phase plate. The focused fields of radially polarized vortex beams with different topological charges at numerical apertures (NAs) of 0.65 and 0.85 are measured respectively, and the results indicate that the total intensity distribution at focus is dependent not only on the NA of the focusing objective lens and polarization pattern of the beam but also on the topological charge l of the beam. Some unique focusing properties of radially polarized vortex beams with fractional topological charges are presented based on numerical calculations. The experimental verification paves the way for some practical applications of radially polarized vortex beams, such as in optical trapping, near-field microscopy, and material processing. 相似文献
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A. I. Lomtev 《JETP Letters》2000,71(10):426-429
The magnetic structure of an isolated two-dimensional Pearl vortex uniformly moving in a thin magnetic superconductor film is studied. The moving process and the magnetic subsystem sizably renormalize the Pearl vortex field and induce the formation of an “inversion wake” behind the vortex at a large distance on the order of 10λ eff from its center. The effect can be observed in the magneto-optical experiments. 相似文献
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A model according to which “fast” and “exotic” negative ions in superfluid helium are the localized states of electrons in vortex rings has been presented. The quantization of radial and longitudinal motions of electrons inside the vortex core and the quantization of the vortex motion of liquid helium lead to the existence of a whole family of excited states of electron vortices, in qualitative agreement with the experiments on the mobility of exotic ions. The possibility of the verification of conclusions of the model in optical experiments has been considered. 相似文献
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We propose and demonstrate the wave front correction of a vortex laser beam by using dual phase only liquid crystal spatial light modulators (LC-SLMs) and a stochastic parallel gradient descent (SPGD) algorithm. One phase only LC-SLM is used to generate vortex laser beam by loading spiral phase screen onto the wave front of input quasi-Gaussian beam. The other phase only LC-SLM under SPGD controller based on the subzone control method adaptively compensates the wave front of vortex laser beam. Numerical simulation and experimental results show that after correction, vortex doughnut like beam is focused into a beam with airy disk pattern distribution in the far field. The adaptive corrections of vortex laser beam with different optical topological charges are studied. The results show that the optical topological charge has little influence on adaptive correction. The powers in the main lobe of far field intensity distributions of vortex laser beams with different optical topological charges are all greatly improved by adaptive correction. The technique proposed in this paper can be used in optical communication, relay mirror and atmospheric turbulence correction. 相似文献
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Tatsuo Kaneyasu Yasumasa Hikosaka Masaki Fujimoto Hiroshi Iwayama Masahito Hosaka Eiji Shigemasa Masahiro Katoh 《Journal of synchrotron radiation》2017,24(5):934-938
The observation of an optical vortex beam at 60 nm wavelength, produced as the second‐harmonic radiation from a helical undulator, is reported. The helical wavefront of the optical vortex beam was verified by measuring the interference pattern between the vortex beam from a helical undulator and a normal beam from another undulator. Although the interference patterns were slightly blurred owing to the relatively large electron beam emittance, it was possible to observe the interference features thanks to the helical wavefront of the vortex beam. The experimental results were well reproduced by simulation. 相似文献
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We present a method for analyzing the wavefront of optical vortices that does not involve interferometry but rather uses surface plasmon polaritons (SPPs). We employ a subwavelength slit in a gold film to cut slices from an optical vortex beam and measure the diffraction of the generated SPPs by scattering them off a second slit. By moving the slits across the vortex beam, we create a tomogram, from which we can determine the vortex charge of the incident beam at a glance. We present results for vortex beams of integer- and half-integer-vortex charge. 相似文献
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用伪色差概念和PW方法设计双折射透镜初始结构 总被引:2,自引:0,他引:2
双焦点干涉显微镜因其高稳定性和高分辨率的特点而受到重视,其核心元件双折射透镜由一片双折射晶体和一片光学玻璃胶合而成。为了双折射透镜的设计工作方便,引入“伪色差”概念,定义“伪色散倒数”,从而可以借用现有的初级像差理论,运用PW方法,给出满足不同设计要求的三种双折射晶体和三种玻璃配对的双胶合透镜的初始结构表格,在不同的应用场合,可用OSLO软件进行像差计算和优化设计,取得需要的结果。为了便于评价这种特定的结构,定义紧凑因子7作为一个评价指标。给出采用方解石和ZF1作材料的设计实例,该设计结构紧凑(γ=0.25)。 相似文献
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利用全息技术在偶氮聚合物薄膜中记录了拓扑荷数q=–1,1,2,4的涡旋光场,并将记录的原始叉形光栅与计算全息光栅进行对比,对不同拓扑荷数涡旋光的记录速率和偶氮材料的可重复擦写性能进行了测试;记录完成后,将复现涡旋光与高斯光束干涉,并与原始涡旋光和原始叉形光栅对比,分析了记录质量.实验结果表明:高阶涡旋光场的全息叉形光栅会在记录过程中发生劈裂,轻微劈裂的涡旋光束仍维持一个稳定的环状结构;全息记录过程中不同拓扑荷数的涡旋光束记录速率较为统一,偶氮材料可经过上百次的擦写而不出现疲劳;再现涡旋光与原始涡旋光在光强分布结构上保持高度一致,再现涡旋光的干涉条纹与原始涡旋全息光栅保持高度一致,涡旋光及其携带的拓扑荷信息可被有效记录和读取. 相似文献