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Propagation properties of Airy Ince–Gaussian wave packets in gradient-index media
摘要： We study localized Airy Ince–Gaussian (AiIG) wave packets in gradient-index (GRIN) media by solving the spatiotemporal evolution equation analytically. The generation and manipulation of AiIG wave packets in GRIN media are affected by the direction of the self-accelerating, elliptical, refractive index distribution parameter, initial velocity and mode number. In addition, energy flow, angular momentum and radiation force, which change periodically, are also thoroughly discussed. The Airy helical Ince–Gaussian wave packets exhibit multiple vortices and carry orbital angular momentum, which have potential applications in optical tweezers and optical communications.
关键词： vortex,Airy Ince–Gaussian wave packets,propagation
更新于2025-09-23 15:23:52
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A cavity depth sensitized Rossiter mode formula
摘要： A depth sensitized Rossiter mode expression for compressible resonant cavity ?ows is derived based on simple shear layer and acoustic concepts. The physics-based result is compared to relevant experiment measurements and empirical models and shows reasonable agreement. Though simple, the cavity depth sensitized Rossiter mode estimate demonstrates the connection between shear layer ?ow and cavity acoustics; moreover, the model provides a useful analytically-based validation metric for detailed resonant cavity simulations.
关键词： Vortex sheet,Rossiter mode,Resonant cavity
更新于2025-09-23 15:23:52
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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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Electromagnetic sinc Schell-model vortex beams
摘要： We introduce a new class of electromagnetic Schell-model source in which the cross-spectral density matrix possesses a sinc correlation function and a separable phase. The far-field radiation properties for the electromagnetic sinc Schell-model vortex beams generated by such source are investigated. It is shown that the far-field distributions of all statistical characteristics of such a beam possess vortex structure, depending on the topological charge and the correlation length of the source field.
关键词： electromagnetic vortex beams,polarization,Coherence
更新于2025-09-23 15:22:29
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Depinning Field of Vortex Domain Wall in Wide Magnetic Wires with Asymmetric Notches Using Magneto-Optical Kerr Effect Microscopy
摘要： We examined the pinning and depinning fields of the vortex domain wall (VDW) in wide permalloy wires to better understand VDW dynamic behavior. Our sample device has differently designed notches at the center of a 2-μm-wide wire. The notch depth ratio ranged from 0.2 to 0.8, and the asymmetric angles of the notches are 45°, 60°, and 75°. The depinning field was found to have two distribution ranges, similar to how the depinning field depends on VDW chirality in submicron size width wire. Our results also showed that the VDW depinning behavior of a wide wire is the same as that of a narrow wire. The asymmetric notch angle affected the depinning field, which was similar to the results of simulation with 400-nm wire. This suggests that the wide wire depinning field is similar to that of narrow wire.
关键词： vortex domain wall,Magneto-optical Kerr effect microscopy,depinning field
更新于2025-09-23 15:22:29
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Propagation properties of a partially coherent anomalous hollow vortex beam in underwater oceanic turbulence
摘要： Based on the extended Huygens–Fresnel principle, the cross-spectral density function of a partially coherent anomalous hollow vortex beam (AHVB) propagating in underwater oceanic turbulence has been derived, and the influences of the beam parameters and underwater oceanic turbulence on the average intensity and coherence properties are investigated by using numerical examples. Our results show that the partially coherent AHVB with smaller coherence length and smaller M will evolve into the flat-topped faster as the propagation distance increases, and the partially coherent AHVB propagating in stronger underwater oceanic turbulence (the larger χT and ? or the smaller ε) will lose the initial dark hollow center and evolve into the Gaussian beam more rapidly. In the influences of oceanic turbulence on the spreading of partially coherent AHVB, it is found that the parameters χT and ? will cause the larger spreading than the parameter ε at the same propagation distance. This research is useful to the practical application of the partially coherent AHVB beam in underwater oceanic turbulence.
关键词： Laser propagation,Vortex beam,Dark hollow beam,Average intensity
更新于2025-09-23 15:22:29
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High-resolution refractometry using phase shifting interferometry based on spatial light modulator and vortex probe
摘要： We present a spatial light modulator (SLM) based phase shifting interferometry (PSI) using an optical vortex for sensing the refractive index (RI) of liquids. The vortex phase rotates according to the phase shift introduced by a medium, and its rotation angle quantifies the index of refraction of the sample. An interferometer modified with the SLM is designed to obtain reliable results. We experimentally demonstrate the stability of the SLM-based system by measuring interference and phase fluctuation. Experimental results show that the proposed system keeps the fluctuation small. The vortex probe PSI combined with the SLM-based interferometer enables not only detecting extremely small changes in concentration but also precisely measuring the RI with high resolution of ～10?? refractive index unit.
关键词： Refractive index sensing,Spatial light modulator,Optical vortex,Interferometry
更新于2025-09-23 15:22:29
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Vortex beam generation with variable topological charge based on a spiral slit
摘要： We propose a vortex beam generator based on a nanometer spiral slit and explore the propagation rule of the topological charge. Compared to the common methods of generation of a vortex beam with a fixed topological charge, the optical vortex generated by the proposed vortex beam generator has the topological charge varying with the propagation distance. The value of topological charge can be modulated by the geometric charge of the spiral slit and the propagation distance. Theoretical analysis predicts the variation rule of the topological charge of vortex beam in the near field, and numerical simulations and experimental measurement verify the proposed scheme. Discussion on the shape and structure of the spiral slit is also presented. This work provides the theoretical foundation for the generation of a vortex field with variable topological charge. The simple geometry of the vortex beam generator and the flexible modulation of the topological charge must inspire applications of the vortex beam.
关键词： optical vortex,near-field diffraction,variable topological charge
更新于2025-09-23 15:22:29
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Even-odd effect in higher-order holographic production of electron vortex beams with nontrivial radial structures
摘要： Structured electron beams carrying orbital angular momentum are currently of considerable interest, both from a fundamental point of view and for application in electron microscopy and spectroscopy. Until recently, most studies have focused on the azimuthal structure of electron vortex beams with well-defined orbital angular momentum. To unambiguously define real electron-beam states and realize them in the laboratory, the radial structure must also be specified. Here we use a specific set of orthonormal modes of electron (vortex) beams to describe both the radial and azimuthal structures of arbitrary electron wavefronts. The specific beam states are based on truncated Bessel beams localized within the lens aperture plane of an electron microscope. We show that their Fourier transform set of beams can be realized at the focal planes of the probe-forming lens using a binary computer-generated electron hologram. Using astigmatic transformation optics, we demonstrate that the azimuthal indices of the diffracted beams scale with the order of the diffraction through phase amplification. However, their radial indices remain the same as those of the encoding beams for all the odd diffraction orders or are reduced to the zeroth order for the even-order diffracted beams. This simple even-odd rule can also be explained in terms of the phase amplification of the radial profiles. We envisage that the orthonormal cylindrical basis set of states could lead to new possibilities in phase contrast electron microscopy and spectroscopy using structured electron beams.
关键词： truncated Bessel beams,astigmatic transformation,computer-generated hologram,electron vortex beams,orbital angular momentum,phase amplification
更新于2025-09-23 15:22:29
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Quantification of Vortex Generation Due to Non-Equilibrium Electrokinetics at the Micro/Nanochannel Interface: Spectral Analysis
摘要： We report on our investigation of a low Reynolds number non-equilibrium electrokinetic ?ow in a micro/nanochannel platform. Non-equilibrium electrokinetic phenomena include so-called concentration polarization in a moderate electric ?eld and vortex formation in a high electric ?eld. We conducted a spectral analysis of non-equilibrium electrokinetic vortices at a micro/nanochannel interface. We found that periodic vortices are formed while the frequency varies with the applied voltages and solution concentrations. At a frequency as high as 60 Hz, vortex generation was obtained with the strongest electric ?eld and the lowest concentration. The power spectra show increasing frequency with increasing voltage or decreasing concentration. We expect that our spectral analysis results will be useful for micromixer developers in the micromachine research ?eld.
关键词： spectral analysis,concentration polarization,micromixer,Vortex generation,electrokinetics,micro/nanochannel
更新于2025-09-23 15:21:21