6,432 research outputs found
Orbital Angular Momentum Waves: Generation, Detection and Emerging Applications
Orbital angular momentum (OAM) has aroused a widespread interest in many
fields, especially in telecommunications due to its potential for unleashing
new capacity in the severely congested spectrum of commercial communication
systems. Beams carrying OAM have a helical phase front and a field strength
with a singularity along the axial center, which can be used for information
transmission, imaging and particle manipulation. The number of orthogonal OAM
modes in a single beam is theoretically infinite and each mode is an element of
a complete orthogonal basis that can be employed for multiplexing different
signals, thus greatly improving the spectrum efficiency. In this paper, we
comprehensively summarize and compare the methods for generation and detection
of optical OAM, radio OAM and acoustic OAM. Then, we represent the applications
and technical challenges of OAM in communications, including free-space optical
communications, optical fiber communications, radio communications and acoustic
communications. To complete our survey, we also discuss the state of art of
particle manipulation and target imaging with OAM beams
Quantum information processing with space-division multiplexing optical fibres
The optical fibre is an essential tool for our communication infrastructure
since it is the main transmission channel for optical communications. The
latest major advance in optical fibre technology is spatial division
multiplexing (SDM), where new fibre designs and components establish multiple
co-existing data channels based on light propagation over distinct transverse
optical modes. Simultaneously, there have been many recent developments in the
field of quantum information processing (QIP), with novel protocols and devices
in areas such as computing, communication and metrology. Here, we review recent
works implementing QIP protocols with SDM optical fibres, and discuss new
possibilities for manipulating quantum systems based on this technology.Comment: Originally submitted version. Please see published version for
improved layout, new tables and updated references following review proces
Compact and high-performance vortex mode sorter for multi-dimensional multiplexed fiber communication systems
With the amplitude, time, wavelength/frequency, phase, and polarization/spin parameter dimensions of the light wave/photon almost fully utilized in both classical and quantum photonic information systems, orbital angular momentum (OAM) carried by optical vortex modes is regarded as a new modal parameter dimension for further boosting the capacity and performance of the systems. To exploit the OAM mode space for such systems, stringent performance requirements on a pair of OAM mode multiplexer and demultiplexer (also known as mode sorters) must be met. In this work, we implement a newly discovered optical spiral transformation to achieve a low-cross-Talk, wide-opticalbandwidth, polarization-insensitive, compact, and robust OAM mode sorter that realizes the desired bidirectional conversion between seven co-Axial OAM modes carried by a ring-core fiber and seven linearly displaced Gaussian-like modes in parallel single-mode fiber channels. We further apply the device to successfully demonstrate high-spectralefficiency and high-capacity data transmission in a 50-km OAM fiber communication link for the first time, in which a multi-dimensional multiplexing scheme multiplexes eight orbital-spin vortex mode channels with each mode channel simultaneously carrying 10 wavelength-division multiplexing channels, demonstrating the promising potential of both the OAM mode sorter and the multi-dimensional multiplexed OAM fiber systems enabled by the device. Our results pave the way for futureOAM-based multi-dimensional communication systems
A Novel Solution to the Dynamic Routing and Wavelength Assignment Problem in Transparent Optical Networks
We present an evolutionary programming algorithm for solving the dynamic
routing and wavelength assignment (DRWA) problem in optical wavelength-division
multiplexing (WDM) networks under wavelength continuity constraint. We assume
an ideal physical channel and therefore neglect the blocking of connection
requests due to the physical impairments. The problem formulation includes
suitable constraints that enable the algorithm to balance the load among the
individuals and thus results in a lower blocking probability and lower mean
execution time than the existing bio-inspired algorithms available in the
literature for the DRWA problems. Three types of wavelength assignment
techniques, such as First fit, Random, and Round Robin wavelength assignment
techniques have been investigated here. The ability to guarantee both low
blocking probability without any wavelength converters and small delay makes
the improved algorithm very attractive for current optical switching networks.Comment: 12 Pages, IJCNC Journal 201
University Optical Fibre Network Access Optimisation: A Case Study
For network access, it is always desired that a fibre optic network connectivity be the major area of
cost minimization, while keeping quality of service as high as possible. This is because overall cost of
setting up a fibre optic cable route is usually very high in relation to other components of the network.
In this study, three buildings clusters were mapped to the University Network Operating Center, and
the network was developed as a fail-safe network, so that in the case of damage to a cable or
connecting component, users are not cut out. The problem was formulated as a Mathematical
Programming problem and solved the resulting transportation problem using MATLAB linear
programming solution. Results from the mathematical model shows an optimized cost for which a
fibre Optic network connectivity can be further develope
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