56 results match your criteria momentum oam-based


Orbital-angular-momentum-resolved diagnostics for tracking internal phase evolution in multi-bound solitons.

Opt Express 2021 May;29(11):16686-16694

The generation of multi-bound solitons is a fascinating subject of investigation in many conservative and dissipative systems, such as photonics, fluid mechanics, Bose-Einstein condensates, and so on. In this study, we demonstrate the successful extraction of phase dynamics between solitons in bound multiple solitons with up to seven constituents in a mode-locked Er laser system. By mapping the internal phase motions of multi-bound solitons to the spatial phase movement of cylindrical vector beams using orbital angular momentum (OAM)-based diagnostics, different categories of internal pulsations are revealed. Read More

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Spiral spectrum of high-order elliptic Gaussian vortex beams in a non-Kolmogorov turbulent atmosphere.

Opt Express 2021 May;29(11):16056-16072

In a free space optical communication system based on vortex beams, the effects of spread and crosstalk caused by atmospheric turbulence should not be ignored. The orbital angular momentum (OAM) spectrum of the signal based on elliptic Gaussian beam (EGB) after propagation through non-Kolmogorov turbulent atmosphere are deduced, and a theoretical model of the spiral spectrum of EGB propagating through turbulent atmosphere is obtained. Numerically calculated OAM modes detection and crosstalk probability under different ellipticity parameters. Read More

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Experimental demonstration of multiple dimensional coding decoding for image transfer with controllable vortex arrays.

Sci Rep 2021 Jun 8;11(1):12012. Epub 2021 Jun 8.

School of Communication and Information Engineering, Chongqing University of Posts and Telecommunications, Chongqing, 400065, China.

Vortex beams carrying orbital angular momentum (OAM), which featuring helical phase front, have been regarded as an alternative spatial degree of freedom for optical mode coding and multiplexing. For most reported OAM-based mode coding schemes, data information is only encoded by different OAM mode states. In this paper, we introduce a novel design technique to construct vortex array phase grating (VAPGs) for the flexible generation of vortex arrays, and employ the proposed VAPGs to realize multi-dimensional space/mode/amplitude coding/decoding. Read More

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Experimental demonstration of OAM-based transmitter mode diversity data transmission under atmosphere turbulence.

Opt Express 2021 Apr;29(9):13171-13182

Twisted light carrying orbital angular momentum (OAM), which features helical phase front, has shown its potential applications in diverse areas, especially in optical communications. For OAM-based free-space optical (FSO) links, a significant challenge is the power fading induced by atmospheric turbulence. In this paper, we experimentally demonstrate the mitigation of atmospheric turbulence effects with an OAM-based transmitter mode diversity scheme. Read More

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Propagation characteristics of the perfect vortex beam in anisotropic oceanic turbulence.

Appl Opt 2020 Nov;59(32):9956-9962

The propagation model of orbital angular momentum (OAM) modes carried by the perfect vortex (pv) beam through anisotropic oceanic turbulence links is established and the factors influencing the OAM propagation are discussed. The findings show that the self-focusing property of pv beams is beneficial to the propagation of OAM modes: a smaller topological charge, a smaller initial radius, and an optimized half-ring width can alleviate degrading effects of turbulence on the pv beam. Additionally, the pv beam with a longer wavelength is more resistant to turbulent interference. Read More

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November 2020

Spectrum Decomposition-Based Orbital Angular Momentum Communication of Acoustic Vortex Beams Using Single-Ring Transceiver Arrays.

IEEE Trans Ultrason Ferroelectr Freq Control 2021 Apr 26;68(4):1399-1407. Epub 2021 Mar 26.

The orbital angular momentum (OAM)-based acoustic vortex (AV) communication has been proven to provide a topological spinning characteristics for data transmission with an improved channel capacity, exhibiting good application prospects in underwater acoustic communications. To improve the accuracy and efficiency of data communication, the spectrum decomposition of OAM modes for OAM-multiplexed AV beams is studied with a simplified structure of single-ring transceiver arrays. The principle of spectrum decomposition for the single-OAM or OAM-multiplexed AV beams is derived based on the phase-coded approach and the orthogonal property of AVs. Read More

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Sound vortex diffraction via topological charge in phase gradient metagratings.

Sci Adv 2020 Oct 2;6(40). Epub 2020 Oct 2.

School of Physical Science and Technology, Soochow University, Suzhou 215006, China.

Wave fields with orbital angular momentum (OAM) have been widely investigated in metasurfaces. By engineering acoustic metasurfaces with phase gradient elements, phase twisting is commonly used to obtain acoustic OAM. However, it has limited ability to manipulate sound vortices, and a more powerful mechanism for sound vortex manipulation is strongly desired. Read More

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October 2020

Computational imaging with low-order OAM beams at microwave frequencies.

Sci Rep 2020 Jul 15;10(1):11641. Epub 2020 Jul 15.

College of Electronic Science and Technology, National University of Defense Technology, Changsha, 410073, China.

With the distinguished wavefront characteristics of vortex electromagnetic wave carrying orbital angular momentum (OAM), the OAM beams have been exploited for radar imaging in recent years. In this paper, the computational imaging model is built using OAM wave, which enables the target reconstruction with limited measurements. The measurement matrix is designed, and the target reconstruction method is proposed in the Cartesian coordinate. Read More

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Orbital-Driven Rashba Effect in a Binary Honeycomb Monolayer AgTe.

Phys Rev Lett 2020 May;124(17):176401

Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.

The Rashba effect is fundamental to the physics of two-dimensional electron systems and underlies a variety of spintronic phenomena. It has been proposed that the formation of Rashba-type spin splittings originates microscopically from the existence of orbital angular momentum (OAM) in the Bloch wave functions. Here, we present detailed experimental evidence for this OAM-based origin of the Rashba effect by angle-resolved photoemission (ARPES) and two-photon photoemission experiments for a monolayer AgTe on Ag(111). Read More

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Orbit Angular Momentum MIMO with Mode Selection for UAV-Assisted A2G Networks.

Sensors (Basel) 2020 Apr 17;20(8). Epub 2020 Apr 17.

School of Communication and Information Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China.

As an emerging solution for line-of-sight (LOS) wireless communications, in air-to-ground (A2G) channels, the unmanned aerial vehicle (UAV), and allowing the dynamic and flexible network deployments enables the supplement or/and replacement of the terrestrial base stations (BSs). However, in conventional multiple-input-multiple-output (MIMO) systems, high-speed communications are significantly limited by channel crosstalks and spectrum scarcities. An orbit angular momentum (OAM) wireless network, allowing co-existence of multiple physical channels within the same frequency band, offers new degrees of freedom to address this dilemma. Read More

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Emission of orbital angular momentum based on spoof localized surface plasmons.

Opt Lett 2019 Dec;44(23):5735-5738

An approach to producing the orbital angular momentum (OAM) based on spoof localized surface plasmons (spoof LSPs) in microwave frequencies is demonstrated both theoretically and experimentally. The fundamental and high-order modes of spoof LSPs occur when a textured metallic surface is excited with a microstrip line. Two orthogonal modes of spoof LSPs with +90° or -90° phase retardation are superimposed, resulting in a OAM-vortex mode. Read More

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December 2019

Spiral spectrum of a Laguerre-Gaussian beam propagating in anisotropic non-Kolmogorov turbulent atmosphere along horizontal path.

Opt Express 2019 Sep;27(18):25342-25356

Close to the ground, it is generally known that atmospheric turbulence exhibits strong anisotropy, which affects the performance of applications such as free-space optical (FSO) communication. In this paper, we establish a theoretical model for calculating the spiral spectrum, also called the orbital angular momentum (OAM) spectrum, of a Laguerre-Gaussian (LG) beam after propagation through anisotropic turbulence along a horizontal link. This model isolates the effects of anisotropy from other parameters of the turbulence. Read More

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September 2019

Polarization controllable generation of flat superimposed OAM states based on metasurface.

Opt Express 2019 Jul;27(15):20133-20144

In this paper, two kind of metasurface-based flat orbital angular momentum (OAM) superposition-state generators are proposed, which can generate OAM superposition states possessing tens of OAM modes being evenly spaced by topological charge number 1. The power spectra of the generated OAM superposition states are flat. The power variation of the OAM modes of the OAM superposition states from one generator is less than 3 dB, and the power variation of the OAM modes of the OAM superposition states from the other one is less than 0. Read More

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High harmonic generation spectroscopy via orbital angular momentum.

J Chem Phys 2019 Aug;151(8):084308

Department of Physics, University of Connecticut, Storrs, Connecticut 06269-3046, USA.

We present an experimental technique using orbital angular momentum (OAM) in a fundamental laser field to drive high harmonic generation (HHG). The mixing of beams with different OAM allows us to generate two laser foci tightly spaced which generate harmonics that interfere in the far field. Thus, this technique is an OAM based in situ HHG interferometric spectroscopic method. Read More

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All-dielectric metasurface grating for on-chip multi-channel orbital angular momentum generation and detection.

Opt Express 2019 Jun;27(13):18794-18802

Optical vortices, carrying quantized orbital angular momentum (OAM) states, have been widely investigated because of their promising applications in both classical and quantum realms. Among these applications, efficient generation and measurement of OAM beams are critical. Current techniques available for generating OAM beams generally suffer from bulky size, low operation efficiency, or single-function or complicated fabrication processes. Read More

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Effects of orbital angular momentum on few-cycle and sub-cycle pulse shapes: coupling between the temporal and angular momentum degrees of freedom.

Authors:
Miguel A Porras

Opt Lett 2019 May;44(10):2538-2541

We describe the effects of the coupling between the orbital angular momentum (OAM) and the temporal degrees of freedom in pulsed Laguerre-Gauss beams as a significant increase of the duration of few-cycle pulses when the OAM carried by the pulse is large, and as an enhancement to other previously known spatiotemporal couplings as radial red- and blue-shift of the mean frequency. In contrast to other detrimental, but retrievable, effects in the generation and propagation of ultrashort vortices such as spatial, group velocity, and topological charge dispersions, the OAM-temporal coupling effect is unavoidable and, therefore, has an impact on applications such as OAM-based optical communications, or on the generation of vortex-carrying attosecond pulses. Read More

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Twisted magnon beams carrying orbital angular momentum.

Nat Commun 2019 05 7;10(1):2077. Epub 2019 May 7.

Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099, Halle (Saale), Germany.

Low-energy eigenmode excitations of ferromagnets are spin waves or magnons that can be triggered and guided in magnonic circuits without Ohmic losses and hence are attractive for communicating and processing information. Here we present new types of spin waves that carry a definite and electrically controllable orbital angular momentum (OAM) constituting twisted magnon beams. We show how twisted beams emerge in magnonic waveguides and how to topologically quantify and steer them. Read More

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Reducing the cross-talk among different orbital angular momentum modes in turbulent atmosphere by using a focusing mirror.

Opt Express 2019 Apr;27(7):10280-10287

The cross-talk among different orbital angular momentum (OAM) modes induced by the turbulent atmosphere is a challenging effect commonly occurring in OAM-based free-space optical (FSO) communication. The aim of this study is to propose a simple method to reduce the crosstalk and demonstrate its effect by analytical derivation and numerical simulation. It is found that the crosstalk is largely reduced by using a focusing mirror. Read More

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Upper Bound to the Orbital Angular Momentum Carried by an Ultrashort Pulse.

Authors:
Miguel A Porras

Phys Rev Lett 2019 Mar;122(12):123904

Grupo de Sistemas Complejos, ETSIME, Universidad Politécnica de Madrid, Rios Rosas 21, 28003 Madrid, Spain.

Photons in a ring-shaped vortex light beam can have an arbitrarily high orbital angular momentum (OAM) lℏ, in addition to the spin angular momentum ±ℏ. For a pulsed vortex beam, there is, however, an upper bound to the integer units l of OAM, or topological charge of the vortex, and a lower bound to the pulse duration to carry OAM. These limits have implications in experiments with ultrashort vortices, e. Read More

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Orbital angular momentum generation in two-mode fiber, based on the modal interference principle.

Opt Lett 2019 Feb;44(4):999-1002

In this Letter, we demonstrate, to the best of our knowledge, a novel method to generate an orbital angular momentum (OAM) based on the principle of the modal interference in a two-mode fiber. At the interference dips, the left- or right-handed circular polarized HE modes can be ideally converted into the ±1-order OAM beam. To verify this concept, we employed the femtosecond laser micro-processing technology to write micro-waveguides in the two-mode fiber and hence realized the in-line modal interferometer. Read More

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February 2019

Generating Dual-Mode Dual-Polarization OAM Based on Transmissive Metasurface.

Sci Rep 2019 Jan 14;9(1):97. Epub 2019 Jan 14.

School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, 610054, China.

Recent advances in electromagnetic (EM) waves with helical phase wave-front carrying orbital angular momentum (OAM) has drawn great attention, since it is believed to be a promising candidate for the next generation of wireless communication technology. To make the design more practical, here, a transmissive metasurface for generating dual-mode and dual-polarization OAM has been designed, manufactured and experimentally validated. To generate EM waves carrying OAM, the element structure is well-designed and can introduce additional phase to the incident wave. Read More

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January 2019

Adaptive turbulence compensation with a hybrid input-output algorithm in orbital angular momentum-based free-space optical communication.

Appl Opt 2018 Sep;57(26):7644-7650

Atmospheric turbulence is a major challenge for practical orbital angular momentum (OAM)-based free-space optical (FSO) communication systems that causes intermodal crosstalk and degrades the performance of the system. Herein, we propose a hybrid input-output algorithm (HIOA)-based adaptive optics (AO) system to compensate for distorted OAM beams. The principle and parameters of the HIOA-based AO system in an OAM-based FSO system are analyzed, and the performance is discussed. Read More

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September 2018

A Novel Scheme for MIMO-SAR Systems Using Rotational Orbital Angular Momentum.

Sensors (Basel) 2018 Oct 18;18(10). Epub 2018 Oct 18.

School of Electronic & Information Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China.

The vortex electromagnetic (EM) wave with orbital angular momentum (OAM) brings a new degree of freedom for synthetic aperture radar (SAR) imaging, although to date, its application to multi-input multi-output (MIMO) SAR has not yet been widely reported. In this paper, an orbital angular momentum (OAM)-based MIMO-SAR system is proposed. The rotational Doppler Effect (RDE) of vortex EM waves offers a novel scheme for an OAM-based MIMO-SAR system. Read More

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October 2018

Close-packed optical vortex lattices with controllable structures.

Opt Express 2018 Sep;26(18):22965-22975

As a spatial structured light field, the optical vortex (OV) has attracted extensive attention in recent years. In practice, the OV lattice (OVL) is an optimal candidate for applications of orbital angular momentum (OAM)-based optical communications, microparticle manipulation, and micro/nanofabrication. However, traditional methods for producing OVLs meet a significant challenge: the OVL structures cannot be adjusted freely and form a close-packed arrangement, simultaneously. Read More

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September 2018

Performance analysis of a LDPC coded OAM-based UCA FSO system exploring linear equalization with channel estimation over atmospheric turbulence.

Opt Express 2018 Aug;26(17):22182-22196

A low-density parity-check (LDPC) coded orbital angular momentum (OAM)-based uniform circular array (UCA) free space optical (FSO) system exploring linear equalization is investigated with channel estimation over the atmospheric turbulence fading channels. On the basis of the proposed system model, the least square (LS) channel estimator is adopted to obtain the channel state information (CSI) of this OAM-FSO system. Then, the average bit error ratio (ABER) expressions with M-ary phase shift keying (MPSK) modulation scheme are derived by ensemble average with the aid of the large number theorem. Read More

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Orbital angular momentum sidebands of vortex beams transmitted through a thin metamaterial slab.

Opt Express 2018 Jun;26(13):17378-17387

A pure vortex beam carrying m-order orbital angular momentum (OAM) will be deformed when transmitting through a thin slab, and "neighboring" sideband {m + 1} and {m-1} modes will emerge. The emergence of the OAM sideband is accompanied with OAM-dependent Goos-Hänchen (GH) shift. When the energies carried by the {m} mode of the transmitted beam and by the sideband modes are identical, the OAM-dependent shifts reach their upper limits, |m|w/2(|m| + 1)1/2, where w is the incident beam waist. Read More

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Restriction on orbital angular momentum distribution: a role of media in vortex beams propagation.

Opt Express 2018 Jun;26(13):17227-17235

The vortex beam carrying single orbital angular momentum (OAM) propagating through a medium with a certain transmission function is investigated. We show that the OAM mode weights in the output OAM spectrum involve two factors: the radial distribution of output beam power and the proposed restriction-characterized function. Based on the restriction-characterized function, we show that the OAM mode weights can only vary in a limited range. Read More

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Controlling abruptly autofocusing vortex beams to mitigate crosstalk and vortex splitting in free-space optical communication.

Opt Express 2018 May;26(10):12605-12619

Orbital angular momentum (OAM) mode crosstalk induced by atmospheric turbulence is a challenging phenomenon commonly occurring in OAM-based free-space optical (FSO) communication. Recent advances have facilitated new practicable methods using abruptly autofocusing light beams for weakening the turbulence effect on the FSO link. In this work, we show that a circular phase-locked Airy vortex beam array (AVBA) with sufficient elements has the inherent ability to form an abruptly autofocusing light beam carrying OAM, and its focusing properties can be controlled on demand by adjusting the topological charge values and locations of these vortices embedded in the array elements. Read More

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Directly using 8.8-km conventional multi-mode fiber for 6-mode orbital angular momentum multiplexing transmission.

Opt Express 2018 Apr;26(8):10038-10047

Twisted light carrying orbital angular momentum (OAM), which featuring helical phase front, has shown its potential applications in diverse areas, especially in optical communications in free space and specially designed fibers, e.g. a vortex fiber. Read More

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Angular lens.

Opt Express 2018 Apr;26(7):8709-8718

We propose a single phase-only optical element that transforms different orbital angular momentum (OAM) modes into localized spots at separated angular positions on a transverse plane. We refer to this element as an angular lens since it separates out OAM modes in a manner analogous to how a converging lens separates out transverse wave-vector modes at the focal plane. We also simulate the proposed angular lens using a spatial light modulator and experimentally demonstrate its working. Read More

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