Optical communications using orbital angular momentum beams
TL;DR: In this article, the authors review recent progress in OAM beam generation/detection, multiplexing/demultiplexing, and its potential applications in different scenarios including free-space optical communications, fiber-optic communications, and RF communications.
Abstract: Orbital angular momentum (OAM), which describes the “phase twist” (helical phase pattern) of light beams, has recently gained interest due to its potential applications in many diverse areas. Particularly promising is the use of OAM for optical communications since: (i) coaxially propagating OAM beams with different azimuthal OAM states are mutually orthogonal, (ii) inter-beam crosstalk can be minimized, and (iii) the beams can be efficiently multiplexed and demultiplexed. As a result, multiple OAM states could be used as different carriers for multiplexing and transmitting multiple data streams, thereby potentially increasing the system capacity. In this paper, we review recent progress in OAM beam generation/detection, multiplexing/demultiplexing, and its potential applications in different scenarios including free-space optical communications, fiber-optic communications, and RF communications. Technical challenges and perspectives of OAM beams are also discussed.
Citations
More filters
TL;DR: The authors survey the steady refinement of techniques used to create optical vortices, and explore their applications, which include sophisticated optical computing processes, novel microscopy and imaging techniques, the creation of ‘optical tweezers’ to trap particles of matter, and optical machining using light to pattern structures on the nanoscale.
Abstract: Thirty years ago, Coullet et al. proposed that a special optical field exists in laser cavities bearing some analogy with the superfluid vortex. Since then, optical vortices have been widely studied, inspired by the hydrodynamics sharing similar mathematics. Akin to a fluid vortex with a central flow singularity, an optical vortex beam has a phase singularity with a certain topological charge, giving rise to a hollow intensity distribution. Such a beam with helical phase fronts and orbital angular momentum reveals a subtle connection between macroscopic physical optics and microscopic quantum optics. These amazing properties provide a new understanding of a wide range of optical and physical phenomena, including twisting photons, spin-orbital interactions, Bose-Einstein condensates, etc., while the associated technologies for manipulating optical vortices have become increasingly tunable and flexible. Hitherto, owing to these salient properties and optical manipulation technologies, tunable vortex beams have engendered tremendous advanced applications such as optical tweezers, high-order quantum entanglement, and nonlinear optics. This article reviews the recent progress in tunable vortex technologies along with their advanced applications.
1,016 citations
University of Queensland1, University of the Witwatersrand2, University of Bristol3, University of East Anglia4, University of Arizona5, University of Münster6, Max Planck Society7, University of Ottawa8, Istituto Nazionale di Fisica Nucleare9, University of Glasgow10, Innsbruck Medical University11, State University of New York System12, The Institute of Optics13, Polytechnic University of Catalonia14, University of Victoria15, University of Southern California16, University of Oregon17, Purdue University18
TL;DR: In this paper, the key fields within structured light from the perspective of experts in those areas, providing insight into the current state and the challenges their respective fields face, as well as the exciting prospects for the future that are yet to be realized.
Abstract: Structured light refers to the generation and application of custom light fields. As the tools and technology to create and detect structured light have evolved, steadily the applications have begun to emerge. This roadmap touches on the key fields within structured light from the perspective of experts in those areas, providing insight into the current state and the challenges their respective fields face. Collectively the roadmap outlines the venerable nature of structured light research and the exciting prospects for the future that are yet to be realized.
639 citations
TL;DR: A brief review of the research in the field to date is examined and what future directions might hold is considered.
Abstract: Twenty-five years ago Allen, Beijersbergen, Spreeuw, and Woerdman published their seminal paper establishing that light beams with helical phase-fronts carried an orbital angular momentum. Previously orbital angular momentum had been associated only with high-order atomic/molecular transitions and hence considered to be a rare occurrence. The realization that every photon in a laser beam could carry an orbital angular momentum that was in excess of the angular momentum associated with photon spin has led both to new understandings of optical effects and various applications. These applications range from optical manipulation, imaging and quantum optics, to optical communications. This brief review will examine some of the research in the field to date and consider what future directions might hold.
551 citations
01 Jul 2021
TL;DR: This work rigorously discusses the fundamental changes required in the core networks of the future, such as the redesign or significant reduction of the transport architecture that serves as a major source of latency for time-sensitive applications.
Abstract: Mobile communications have been undergoing a generational change every ten years or so. However, the time difference between the so-called “G’s” is also decreasing. While fifth-generation (5G) systems are becoming a commercial reality, there is already significant interest in systems beyond 5G, which we refer to as the sixth generation (6G) of wireless systems. In contrast to the already published papers on the topic, we take a top-down approach to 6G. More precisely, we present a holistic discussion of 6G systems beginning with lifestyle and societal changes driving the need for next-generation networks. This is followed by a discussion into the technical requirements needed to enable 6G applications, based on which we dissect key challenges and possibilities for practically realizable system solutions across all layers of the Open Systems Interconnection stack (i.e., from applications to the physical layer). Since many of the 6G applications will need access to an order-of-magnitude more spectrum, utilization of frequencies between 100 GHz and 1 THz becomes of paramount importance. As such, the 6G ecosystem will feature a diverse range of frequency bands, ranging from below 6 GHz up to 1 THz. We comprehensively characterize the limitations that must be overcome to realize working systems in these bands and provide a unique perspective on the physical and higher layer challenges relating to the design of next-generation core networks, new modulation and coding methods, novel multiple-access techniques, antenna arrays, wave propagation, radio frequency transceiver design, and real-time signal processing. We rigorously discuss the fundamental changes required in the core networks of the future, such as the redesign or significant reduction of the transport architecture that serves as a major source of latency for time-sensitive applications. This is in sharp contrast to the present hierarchical network architectures that are not suitable to realize many of the anticipated 6G services. While evaluating the strengths and weaknesses of key candidate 6G technologies, we differentiate what may be practically achievable over the next decade, relative to what is possible in theory. Keeping this in mind, we present concrete research challenges for each of the discussed system aspects, providing inspiration for what follows.
529 citations
Cites background from "Optical communications using orbita..."
...Since OAM performs better with electrically larger antennas, it is better suited for high mmWaves and THz systems and, in particular, for free-space optics applications (see [8] and [118])....
[...]
TL;DR: In this paper, the basic concepts of polarization/phase vortex modulation and multiplexing in communications and key techniques of polarization and phase vortex generation and (de)multiplexing are introduced.
Abstract: An optical vortex having an isolated point singularity is associated with the spatial structure of light waves. A polarization vortex (vector beam) with a polarization singularity has spatially variant polarizations. A phase vortex with phase singularity or screw dislocation has a spiral phase front. The optical vortex has recently gained increasing interest in optical trapping, optical tweezers, laser machining, microscopy, quantum information processing, and optical communications. In this paper, we review recent advances in optical communications using optical vortices. First, basic concepts of polarization/phase vortex modulation and multiplexing in communications and key techniques of polarization/phase vortex generation and (de)multiplexing are introduced. Second, free-space and fiber optical communications using optical vortex modulation and optical vortex multiplexing are presented. Finally, key challenges and perspectives of optical communications using optical vortices are discussed. It is expected that optical vortices exploiting the space physical dimension of light waves might find more interesting applications in optical communications and interconnects.
523 citations
References
More filters
TL;DR: Laser light with a Laguerre-Gaussian amplitude distribution is found to have a well-defined orbital angular momentum and an astigmatic optical system may be used to transform a high-order LaguERre- Gaussian mode into aHigh-order Hermite-Gaussia mode reversibly.
Abstract: Laser light with a Laguerre-Gaussian amplitude distribution is found to have a well-defined orbital angular momentum. An astigmatic optical system may be used to transform a high-order Laguerre-Gaussian mode into a high-order Hermite-Gaussian mode reversibly. An experiment is proposed to measure the mechanical torque induced by the transfer of orbital angular momentum associated with such a transformation.
7,918 citations
"Optical communications using orbita..." refers background in this paper
...thus can be viewed to carry both spin angular momentum (SAM) and OAM [4]....
[...]
TL;DR: In this article, a two-dimensional array of optical resonators with spatially varying phase response and subwavelength separation can imprint phase discontinuities on propagating light as it traverses the interface between two media.
Abstract: Conventional optical components rely on gradual phase shifts accumulated during light propagation to shape light beams. New degrees of freedom are attained by introducing abrupt phase changes over the scale of the wavelength. A two-dimensional array of optical resonators with spatially varying phase response and subwavelength separation can imprint such phase discontinuities on propagating light as it traverses the interface between two media. Anomalous reflection and refraction phenomena are observed in this regime in optically thin arrays of metallic antennas on silicon with a linear phase variation along the interface, which are in excellent agreement with generalized laws derived from Fermat’s principle. Phase discontinuities provide great flexibility in the design of light beams, as illustrated by the generation of optical vortices through use of planar designer metallic interfaces.
6,763 citations
[...]
TL;DR: A protocol for coin-tossing by exchange of quantum messages is presented, which is secure against traditional kinds of cheating, even by an opponent with unlimited computing power, but ironically can be subverted by use of a still subtler quantum phenomenon, the Einstein-Podolsky-Rosen paradox.
5,126 citations
Book•
01 Jun 1998
TL;DR: In this paper, a line-of-sight propagation of Gaussian-Beam waves in the atmosphere has been studied in the context of beam statistics mathematica programmes.
Abstract: Random Processes and Random Fields Optical Turbulence in the Atmosphere Free-Space Propagation of Gaussian-Beam Waves Classical Theory of Optical Wave Propagation Line-of-Sight Propagation - Weak Fluctuation Theory, Part 1 Line-of-Sight Propagation - Weak Fluctuation Theory, Part 2 Propagation Through Random Phase Screens Laser Satellite Communication Systems Propagation Through Complex Paraxial ABCD Optical Systems Doublepassage Problems - Laser Radar Systems Line-of-Sight Propagation - Strong Fluctuation Theory Appendices - Special Functions Integral Table Tables of Beam Statistics Mathematica Programmes.
3,633 citations
"Optical communications using orbita..." refers background in this paper
...Due to the fact that turbulence effects are almost independent of the light polarization [64], the probe beam is orthogonally polarized as compared to all of theother beams so that it is convenient to separate it at the receiver end....
[...]
...It is known that inhomogeneities in the temperature and pressure of the atmosphere lead to random variations in the refractive index along the transmission path, and can easily distort the phase front of a light beam [64,65]....
[...]