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Ronald L Cappelletti, Terrence Jach, John Vinson
It has been shown that single-particle wave functions, of both photons and electrons, can be created with a phase vortex, i.e., an intrinsic orbital angular momentum (OAM). A recent experiment has claimed similar success using neutrons [C. W. Clark et al., Nature, 525, 504 (2015)NATUAS0028-083610.1038/nature15265]. We show that their results are insufficient to unambiguously demonstrate OAM, and they can be fully explained as phase contrast interference patterns. Furthermore, given the small transverse coherence length of the neutrons in the original experiment, the probability that any neutron was placed in an OAM state is vanishingly small...
March 2, 2018: Physical Review Letters
Chang-Hwan Yi, Julius Kullig, Jan Wiersig
One of the interesting features of open quantum and wave systems is the non-Hermitian degeneracy called an exceptional point, where not only energy levels but also the corresponding eigenstates coalesce. We demonstrate that such a degeneracy can appear in optical microdisk cavities by deforming the boundary extremely weakly. This surprising finding is explained by a semiclassical theory of dynamical tunneling. It is shown that the exceptional points come in nearly degenerated pairs, originating from the different symmetry classes of modes...
March 2, 2018: Physical Review Letters
Shimao Li, Yunhong Ding, Xiaowei Guan, Heyun Tan, Zhichao Nong, Lin Wang, Lin Liu, Lidan Zhou, Chunchuan Yang, Kresten Yvind, Leif Katsuo Oxenløwe, Siyuan Yu, Xinlun Cai
Photonic integrated devices that emit vortex beam carrying orbital angular momentum are becoming key components for multiple applications. Here we propose and demonstrate a high-efficiency vortex beam emitter based on a silicon micro-ring resonator integrated with a metal mirror. Such a compact emitter is capable of generating vortex beams with a high efficiency and small divergence angle. Vector vortex beams of various topological charges are selectively generated by the emitter at different wavelengths with an emission efficiency of up to 37%...
March 15, 2018: Optics Letters
Zengkai Shao, Jiangbo Zhu, Yanfeng Zhang, Yujie Chen, Siyuan Yu
Cylindrical vector vortex (CVV) beams, complex light fields that exhibit a vector nature and carry quantized orbital angular momentum (OAM) states, have been widely investigated due to their rich applications. Current technologies to generate CVV beams using individual polarization and spatial phase manipulations suffer from bulky size and low configurability. In this Letter, we propose and experimentally demonstrate an approach to generate CVV beams with a single integrated device based on a silicon nitride microring resonator and embedded top-gratings...
March 15, 2018: Optics Letters
Z H Zhong, R X Tang, M Zhou, X H Deng, Y Pang, W R Paterson, B L Giles, J L Burch, R B Tobert, R E Ergun, Y V Khotyaintsev, P-A Lindquist
Secondary flux ropes are suggested to play important roles in energy dissipation and particle acceleration during magnetic reconnection. However, their generation mechanism is not fully understood. In this Letter, we present the first direct evidence that a secondary flux rope was generated due to the evolution of an electron vortex, which was driven by the electron Kelvin-Helmholtz instability in an ion diffusion region as observed by the Magnetospheric Multiscale mission. The subion scale (less than the ion inertial length) flux rope was embedded within the electron vortex, which contained a secondary electron diffusion region at the trailing edge of the flux rope...
February 16, 2018: Physical Review Letters
An-Ci Shih, Chi-Jui Han, Tsung-Cheng Kuo, Yun-Chien Cheng
The deposition stability and homogeneity of microparticles improved with mask, lengthened nozzle and flow rate adjustment. The microparticles can be used to encapsulate monomers, before the monomers in the microparticles can be deposited onto a substrate for nanoscale self-assembly. For the uniformity of the synthesized nanofilm, the homogeneity of the deposited microparticles becomes an important issue. Based on the ANSYS simulation results, the effects of secondary flow were minimized with a lengthened nozzle...
March 14, 2018: Nanomaterials
Jose Angel Fernandez-Roldan, Rafael Perez Del Real, Cristina Bran, Manuel Vazquez, Oksana Chubykalo-Fesenko
Diameter-modulated nanowires offer an important paradigm to design the magnetization response of 3D magnetic nanostructures by engineering the domain wall pinning. With the aim to understand its nature and to control the process, we analyze the magnetization response in FeCo periodically modulated polycrystalline nanowires varying the minor segment diameter. Our modelling indicates a very complex behavior with a strong dependence on the disorder distribution and an important role of topologically non-trivial magnetization structures...
March 14, 2018: Nanoscale
Jinfeng Huang, Xiuying Li, Zhiqing Xun, Weifeng Du, Xindong Guo, Yanping Xian, Senyu Lin, Jianhua Tan
A gas chromatography with mass spectrometry method was developed for the simultaneous determination of ten kinds of glycol ethers and their acetates in cosmetics. The samples were extracted with methanol/ethyl acetate (80:20, v/v), further treated with vortex and ultrasound, and analyzed by gas chromatography with mass spectrometry. The concentration of each analyte was calibrated by external standard method. Under the optimal conditions, the analytes showed linear relationship in the range of 0.05-25 mg·L-1 with determination coefficients larger than 0...
March 14, 2018: Journal of Separation Science
Antonio Tursi, Amerigo Beneduci, Francesco Chidichimo, Nicoletta De Vietro, Giuseppe Chidichimo
Remediation of water bodies from petroleum hydrocarbons is of the utmost importance due to health risks related to the high toxicity, mutagenicity and carcinogenicity of the hydrocarbons components that may enter into the food chain. Though several methods were proposed to face up this challenge, they are generally not easily feasible at a contaminated site and quite costly. Here we propose a green, cost-effective technology based on hydrophobized Spanish Broom (SB) cellulose fiber. The natural cellulose fiber was extracted by alkaline digestion of the raw vegetable...
March 7, 2018: Chemosphere
Shan Jiang, Chang Chen, Hualiang Zhang, Weidong Chen
The vortex wave that carries orbital angular momentum has attracted much attention due to the fact that it can provide an extra degree of freedom for optical communication, imaging and other applications. In spite of this, the method of OAM generation at high frequency still suffers from limitations, such as chromatic aberration and low efficiency. In this paper, an azimuthally symmetric electromagnetic metasurface with wide bandwidth is designed, fabricated and experimentally demonstrated to efficiently convert a left-handed (right-handed) circularly polarized incident plane wave (with a spin angular momentum (SAM) of ћ) to a right-handed (left-handed) circularly polarized vortex wave with OAM...
March 5, 2018: Optics Express
Jintao Xie, Jianbin Zhang, Junran Ye, Haowei Liu, Zhuoying Liang, Shangjie Long, Kangzhu Zhou, Dongmei Deng
We introduce the propagation of the first-order chirped Airy vortex beams (FCAiV) in a chiral medium analytically. Results show that the FCAiV beams split into the left circularly polarized vortex (LCPV) beams and the right circularly polarized vortex (RCPV) beams, which have totally different propagation trajectories in the chiral medium. In this paper, we investigate the effects of the first-order chirped parameter β, the chiral parameter γ and the optical vortex on the propagation process of the FCAiV beams...
March 5, 2018: Optics Express
Hai Lin, Wenguo Zhu, Jianhui Yu, Mengjiang Jiang, Linqing Zhuo, Wentao Qiu, Jiangli Dong, Yongchun Zhong, Zhe Chen
The angular Goos-Hänchen shift of vortex beam is investigated theoretically when a Laguerre-Gaussian (LG) beam is reflected by an air-metamaterial interface. The upper limit of the angular GH shift is found to be half of the divergence angle of the incident beam, i.e., |Θup| = (|ℓ| + 1)1/2 /k0 w0 , with ℓ, k0 , and w0 being the vortex charge, wavenumber in vacuum, and beam waist, respectively. Interestingly, the upper limited angular GH shift is accompanied by the upper-limited spatial IF shift. A parameter F is introduced to compare the total beam shift with the beam size...
March 5, 2018: Optics Express
Jingbo Sun, Salih Z Silahli, Wiktor Walasik, Qi Li, Eric Johnson, Natalia M Litchinitser
Colloidal media with well-defined optical properties have been widely used as model systems in many fundamental and applied studies of light-matter interactions in complex media. Recent progress in the field of engineered nanoscale optical materials with fundamentally new physical properties opens new opportunities for tailoring the properties of colloids. In this work, we experimentally demonstrate the evolution of the optical vortex beams of different topological charges propagating in engineered nano-colloidal suspension of negative polarizability with saturable nonlinearities...
March 5, 2018: Optics Express
G Zhou, K P Wang, H W Liu, L Wang, X F Xiao, D D Dou, Y B Fan
Owing to low bearing capacity and efficiency, traditional filters or adsorbents for removal of contaminants like crystal violet (CV) dye required frequent replacement. Besides, the combination of three-dimensional (3D) printing and bionics could break the constraints of traditional configuration. In this study, a novel depth-type hybrid polylactic acid (PLA)@graphene oxide (GO)/chitosan (CS) sponge filter with bionic fish-mouth structure was prepared and fabricated, assisted by 3D printing and double freeze-drying technology, according to the theories of vertical cross-step filtration and swirling flow...
March 9, 2018: International Journal of Biological Macromolecules
Ekaterina Khestanova, John Birkbeck, Mengjian Zhu, Yang Cao, Geliang Yu, Davit Ghazaryan, Jun Yin, Helmuth Berger, László Forró, Takashi Taniguchi, Kenji Watanabe, Roman Vladislavovich Gorbachev, Artem Mishchenko, Andre K Geim, Irina V Grigorieva
It is well known that superconductivity in thin films is generally suppressed with decreasing thickness. This suppression is normally governed by either disorder-induced localization of Cooper pairs, weakening of Coulomb screening, or generation and unbinding of vortex-antivortex pairs as described by the Berezinskii-Kosterlitz-Thouless (BKT) theory. Defying general expectations, few-layer NbSe2 - an archetypal example of ultrathin superconductors - has been found to remain superconducting down to monolayer thickness...
March 12, 2018: Nano Letters
Songling Han, Huijie An, Hui Tao, Lanlan Li, Yuantong Qi, Yongchang Ma, Xiaohui Li, Ruibing Wang, Jianxiang Zhang
We demonstrate that the traditional emulsification theory can be enriched by a self-assembly approach, in which hydrophilic copolymers with one block exhibiting noncovalent forces with the oil phase self-assemble at the oil-water interface, thereby reducing interfacial tension and forming emulsions. This approach was established using affinity diblock copolymers that can interact with oil molecules through electrostatic interactions or hydrogen-bonding. Nanoemulsions with excellent stability were successfully obtained simply via vortexing...
March 12, 2018: Chemical Communications: Chem Comm
Paul S Pagel, Lonnie Dye, Brent T Boettcher, Julie K Freed
OBJECTIVE: Blood flow across the mitral valve during early left ventricular (LV) filling produces a 3-dimensional rotational fluid body, known as a vortex ring, that enhances LV filling efficiency. Diastolic dysfunction is common in elderly patients, but the influence of advanced age on vortex formation is unknown. The authors tested the hypothesis that advanced age is associated with a reduction in LV filling efficiency quantified using vortex formation time (VFT) in octogenarians undergoing coronary artery bypass graft (CABG) surgery...
March 7, 2018: Journal of Cardiothoracic and Vascular Anesthesia
Zhenshan Yang, Xia Zhang, Chenglin Bai, Minghong Wang
We investigate a new class of nondiffracting optical beams carrying fractional orbital angular momentum (FOAM Bessel beams), which can be constructed by modifying the phase step of the spiral phase plate in a setup originally for the generation of traditional Bessel beams. The FOAM Bessel beams have entirely stable vortex structures, and form an infinite number of orthogonal and complete subsets for monochromatic scalar light in free space. With the advantages of structural stability and orthogonality-completeness, the FOAM Bessel beams are expected to be useful for study and application in various fields of modern optics...
March 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Jing Zhu, Pei Zhang, Dongxu Chen, Ruifeng Liu, Yingnan Zhou, Jinwen Wang, Hong Gao, Fuli Li
Precisely determining the topological charge (TC) of both integral Bessel beams (IBB) and fractional Bessel beams (FBB) is a key issue for their applications. However, most of the common methods could not probe both the IBB and FBB precisely and robustly. In this paper, we present a robust method to probe the topological charge of a Bessel beam by dynamic angular double slits (ADSs). We find that when a Bessel beam vertically illuminates on a dynamic ADS, the information of the TC can be retrieved from its Fourier transform patterns near the optical axis...
March 1, 2018: Applied Optics
Pituk Panthong, Sorakrai Srisuphaphon, Surasak Chiangga, Sarayut Deachapunya
We apply the near-field Talbot effect to distinguish, characterize, and detect optical vortices. We perform experiments with single-, double-, multiple-slit, and grating diffraction. High-contrast image detection is achieved with the Talbot effect of a grating, even for higher than l=±1 orbital angular momentum states. Furthermore, we manipulate the vortex beam with different vortex states and use the Talbot effect for detecting. The experimental results are supported by theoretical simulations and demonstrate that the Talbot effect provides an excellent tool for optical vortex detection...
March 1, 2018: Applied Optics
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