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Effect of anisotropic non-Kolmogorov turbulence on the evolution behavior of Gaussian Schell-model vortex beams
摘要： The effect of anisotropic non-Kolmogorov turbulence on the evolution behavior of average intensity and coherent vortices for Gaussian Schell-model (GSM) vortex beams is investigated. Based on the extended Huygens–Fresnel principle and power spectrum of the anisotropic non-Kolmogorov turbulence, the analytical expressions for the cross-spectral density and average intensity of GSM vortex beams propagating through anisotropic non-Kolmogorov turbulence are obtained. The evolution behavior of intensity and coherent vortices for GSM vortex beams in anisotropic non-Kolmogorov turbulence has been discussed in detail by numerical simulation. The results shown that the evolution behavior of coherent vortices and intensity profile depends on the effective anisotropic factor, generalized exponent factor and structure constant of anisotropic non-Kolmogorov turbulence, as well as the beam parameters, such as beam waist, wave length and correlation length.
关键词： Gaussian Schell-model vortex beams,Anisotropic non-Kolmogorov turbulence,Evolution behavior of coherent vortices
更新于2025-09-23 15:23:52
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Generation of polarization-sensitive modulated optical vortices with all-dielectric metasurfaces
摘要： Optical vortices (OVs) created from helical modes of light have extensive applications in optical manipulation, imaging and optical communications. Moreover, modulated optical vortices (MOVs) with modified wavefronts could provide new opportunities for fractionating particles and actuating microelectromechanical systems. Traditional devices for generating MOVs include spatial light modulators, spiral phase plates etc. However, such bulky devices are difficult to be applied to high-level integrated optical systems. Besides, other MOV generators are typically static and polarization-insensitive. Here, we proposed an all-dielectric metasurface to generate polarization-sensitive MOVs. The intensity patterns of the OVs can be modulated by adding a tangential modulation factor in the phase profile. Independent manipulation of two orthogonal polarizations was adopted via tailoring the geometric parameters of silicon (Si) pillars. We experimentally demonstrated that the metasurface could generate a doughnut and an actinomorphic vortex beams for different polarization inputs. In addition, the intensity pattern of the MOVs can be dynamically tuned by adjusting the polarization angle. This work can benefit optical manipulation and can be further extended to visible and near-infrared bands.
关键词： propagation phase,all-dielectric metasurfaces,mid-infrared,polarizations,modulated optical vortices
更新于2025-09-23 15:22:29
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HIFiRE-5 Boundary-Layer Transition Measured in a Mach-6 Quiet Tunnel with Infrared Thermography
摘要： The principal goal of the Hypersonic International Flight Research Experimentation (HIFiRE) flight 5 is to measure hypersonic boundary-layer transition on a three-dimensional body. This paper presents measurements of heat flux and boundary-layer transition in the Boeing/U.S. Air Force Office of Scientific Research Mach-6 Quiet Tunnel. This facility has been developed to provide quiet flow at high Reynolds number, with low noise levels comparable to flight. Previously, the global heat flux and location of the transition front were measured with temperature-sensitive paint (TSP). A new HIFiRE-5 model was built with a polyether ether ketone shell, which is suitable for infrared–thermographic heat-flux measurements. Quiet-flow tests at Reynolds numbers of 8–12 ? 106∕m and zero angle of attack indicate a centerline transition location within 4% of the earlier TSP results, on the order of the uncertainty of the two techniques. This good agreement reinforces confidence in the earlier measurements and the new infrared-based technique. Examination of the off-centerline transition front indicates that the wavelength of stationary crossflow vortices is the same for both models and instrumentation techniques, although the streaks do not coincide precisely.
关键词： crossflow vortices,infrared thermography,Mach-6 quiet tunnel,boundary-layer transition,HIFiRE-5,heat flux
更新于2025-09-23 15:22:29
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Formation of Quantum Vortices at the Ionization of an Atom by an Ultrashort Laser Pulse: Two- and Three-Dimensional Cases
摘要： Quantum vortices formed at the barrier-suppression ionization of an atom by an ultrashort laser pulse have been studied theoretically and numerically. The ionization of a hydrogen atom is considered in the two-dimensional space and the ionization of an atom in the zero-range potential approximation is considered in the three-dimensional space. The resulting analytical expressions imply that the localization of quantum vortices in the three-dimensional space can be predicted by analyzing the two-dimensional model.
关键词： hydrogen atom,zero-range potential approximation,ultrashort laser pulse,Quantum vortices,barrier-suppression ionization
更新于2025-09-23 15:19:57
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Curves, wavefronts and caustics determined by the intensity pattern of an adiffractional beam
摘要： The aim of the present work is threefold, first we show that the intensity pattern of a nondiffracting beam determines an arbitrary positive real function and a complete integral of both the eikonal and Laplace equations on the plane; second, by using this result we associate to the intensity pattern a two-parameter family of curves and a one-parameter family of caustics on the plane and third, we use the intensity pattern of the Bessel beam of order m to identify its maxima with the family of caustics. This result suggests to define a family of caustics as the maxima of a given intensity pattern.
关键词： 070.3185 (Invariant optical fields),050.4865 (Optical vortices),080.0080 (Geometric optics)
更新于2025-09-19 17:15:36
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Controlled creation of a singular spinor vortex by circumventing the Dirac belt trick
摘要： Persistent topological defects and textures are particularly dramatic consequences of superfluidity. Among the most fascinating examples are the singular vortices arising from the rotational symmetry group SO(3), with surprising topological properties illustrated by Dirac’s famous belt trick. Despite considerable interest, controlled preparation and detailed study of vortex lines with complex internal structure in fully three-dimensional spinor systems remains an outstanding experimental challenge. Here, we propose and implement a reproducible and controllable method for creating and detecting a singular SO(3) line vortex from the decay of a non-singular spin texture in a ferromagnetic spin-1 Bose–Einstein condensate. Our experiment explicitly demonstrates the SO(3) character and the unique spinor properties of the defect. Although the vortex is singular, its core fills with atoms in the topologically distinct polar magnetic phase. The resulting stable, coherent topological interface has analogues in systems ranging from condensed matter to cosmology and string theory.
关键词： Bose–Einstein condensate,spinor systems,superfluidity,topological defects,SO(3) vortices
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - A Topologically Robust Formation of Broadband Vortices Propagating at the Speed of Light
摘要： We show that Flying Doughnuts, the exact propagating solutions of Maxwell equations in the form of single-cycle toroidal pulses have complex and robust fine topological structure of spectrally broadband vortices and extended areas of energy backflow. The study of the topology of electromagnetic waves provides insights into their fine-scale structure and can reveal information about their propagation dynamics. Typically, such studies are focused on vortices and polarization singularities of monochromatic light beams [1,2]. Here, we present a study of the singularities in the electromagnetic fields and Poynting vector of a single-cycle toroidal pulse, termed Flying Doughnut (FD). FD pulses are exact solutions of Maxwell's equations with known analytical form. Thus, such exotic forms of light are inherently stable under propagation and can be scrutinised at extraordinary level of detail. FDs propagate in free-space at the speed of light and their interactions with matter include non-trivial field transformations upon reflection from metallic and dielectric interfaces. The field configuration of the FDs is topologically similar to the toroidal dipolar excitations in matter, which allows to excite strong toroidal response and engage anapole modes (non-radiating configurations of electric and toroidal dipoles) in dielectric particles. It has been suggested that the longitudinal field components could be employed for the acceleration of charged particles.
关键词： toroidal pulses,anapole modes,broadband vortices,Maxwell equations,energy backflow,Poynting vector,Flying Doughnuts
更新于2025-09-16 10:30:52
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Magnetic field induced vortices in graphene quantum dots
摘要： The energy spectrum and local current patterns in graphene quantum dots are investigated for different geometries in the presence of an external perpendicular magnetic field. Our results demonstrate that, for specific geometries and edge configurations, the quantum dot exhibits vortex and anti-vortex patterns in the local current density, in close analogy to the vortex patterns observed in the probability density current of semiconductor quantum dots, as well as in the order parameter of mesoscopic superconductors.
关键词： graphene quantum dots,magnetic field,energy spectrum,local current patterns,vortices
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Analytical Mie Theory of Vector Complex Source Vortices and its Application for the Investigation of Planar Chiral Structures
摘要： The Mie theory was the very first description of light interaction with a particle and it was extended for highly focused beams. The polarization properties of highly focused beams are strongly influenced by the size and shape of the focal spot of the beam. The optical response of a nanoparticle is strongly dependent on the polarization state of the incident light and it can be tailored by engineering the polarization state of the incident light. In this work, we theoretically investigate the interaction of vector complex-source vortex beams (VCSBs) with a planar chiral structure placed in the focal plane. We start by expanding VCSBs analytically into vector spherical harmonics (VSHs) and study how the VCSB interacts with a planar chiral structure. We found that for some values of the radial and azimuthal indices there is a strong chiral effect, see Fig. 1 (a), and when the radial and azimuthal indices are changing there is a strong chiral effect, see Fig. 1 (b). In order to better understand the underlying effects we calculate the internal and external fields using the T-matrix approach (see Supplement of Ref. [25]) of such cluster and investigate how the cluster interacts with left (LCP) and right (RCP) circularly polarized light, see Fig. 2. We found, that for some values of radial and azimuthal indices there is a strong chiral effect, see Fig. 1 (a), and when the radial and azimuthal indices are changing there is a strong chiral effect, see Fig. 1 (b). In our numerical investigations we observe that for some values of radial and azimuthal indices there is a strong chiral effect, see Fig. 1 (a), and when the radial and azimuthal indices are changing there is a strong chiral effect, see Fig. 1 (b).
关键词： Mie theory,light interaction,planar chiral structures,polarization,vector complex-source vortices
更新于2025-09-12 10:27:22
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Modeling tomographic measurements of photoelectron vortices in counter-rotating circularly polarized laser pulses
摘要： Recent experiments [D. Pengel, S. Kerbstadt, L. Englert, T. Bayer, and M. Wollenhaupt, Phys. Rev. A 96, 043426 (2017)] have measured the photoelectron momentum distribution for three-photon ionization of potassium by counter-rotating circularly polarized 790-nm laser pulses. The distribution displays spiral vortices, arising from the interference of ionizing wave packets with different magnetic quantum numbers. The high level of multidimensional detail observed in the distribution makes this an ideal case in which to demonstrate the accuracy of emerging theoretical techniques applicable to such problems. We use the R-matrix with time dependence approach to investigate this process. We calculate the full-dimensional photoelectron momentum distribution, and compare against a set of planar projections of this distribution previously measured in experiment.
关键词： multiphoton ionization,potassium,photoelectron vortices,counter-rotating circularly polarized laser pulses,R-matrix with time dependence
更新于2025-09-12 10:27:22