Mitchell Arij Cox

Mitchell Arij Cox
University of the Witwatersrand | wits · School of Electrical and Information Engineering

PhD

About

38
Publications
17,170
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
653
Citations
Introduction
I am interested in free-space optical communications and am currently working on finding ways to improve the range and resilience of free-space links in atmospheric turbulence using spatial modes of light. My research is predominantly experimental.
Additional affiliations
January 2017 - present
University of the Witwatersrand
Position
  • Lecturer
January 2016 - December 2019
University of the Witwatersrand
Position
  • PhD
Description
  • Improving the Resilience of Free-Space Optical Links Using Structured Modes of Light
July 2015 - December 2016
University of the Witwatersrand
Position
  • Lecturer
Education
January 2016 - December 2019
University of the Witwatersrand
Field of study
  • Free-Space Optical Communication
January 2014 - December 2015
University of the Witwatersrand
Field of study
  • HPC for HEP
February 2008 - November 2011
University of the Witwatersrand
Field of study
  • Electrical and Electronic Engineering

Publications

Publications (38)
Article
Full-text available
Free-space optical communication with spatial modes of light has become topical due to the possibility of dramatically increasing communication bandwidth via Mode Division Multiplexing (MDM). While both scalar and vector vortex modes have been used as transmission bases, it has been suggested that the latter is more robust in turbulence. Using orbi...
Article
Full-text available
Free-space communication links are severely affected by atmospheric turbulence, which causes degradation in the transmitted signal. One of the most common solutions to overcome this is to exploit diversity. In this approach, information is sent in parallel using two or more transmitters that are spatially separated, with each beam therefore experie...
Article
Vast geographical distances in Africa are a leading cause for the so-called “digital divide” due to the high cost of installing fibre. Free-Space Optical (FSO) communications offer a convenient and higher bandwidth alternative to point-to-point radio microwave links, with the possibility of re-purposing existing infrastructure. Unfortunately, the r...
Article
Full-text available
With the ever-increasing demand for data and radio frequency spectrum becoming congested, Free Space Optical (FSO) communication may find a niche for situations where fiber is too expensive or too difficult to install. FSO is a cross-disciplinary field that draws from radio and fiber communication, astronomy, and even quantum optics, and it has see...
Article
Full-text available
Optical communication is an integral part of the modern economy, having all but replaced electronic communication systems. Future growth in bandwidth appears to be on the horizon using structured light, encoding information into the spatial modes of light, and transmitting them down fibre and free-space, the latter crucial for addressing last mile...
Preprint
Motivation Genome-wide association studies (GWASs) analyse genetic variation over the genomes of many individuals in an attempt to identify single nucleotide polymorphisms (SNPs) associated with complex phenotypes. To capture a large amount of genetic variation and increase the chance of detecting associated SNPs, modern GWASs include millions of S...
Article
We present a fast and efficient simulation method of structured light free space optics (FSO) channel effects from propagation through a turbulent atmosphere. In a system that makes use of multiple higher order modes (structured light), turbulence causes crosstalk between modes. This crosstalk can be described by a channel matrix, which usually req...
Article
Full-text available
Efficient utilization of the spectrum, increased resilience to inter-symbol interference (ISI) and simpler channel equalization are becoming important considerations in the design of wireless communication systems including visible light communication (VLC) systems. In this regard, orthogonal frequency division multiplexing (OFDM) has become a pref...
Preprint
Nearly three decades since its discovery, orbital angular momentum (OAM) has proven to be highly versatile for a wide range of applications. It is an indispensable tool in quantum optics, has made a significant impact in optical tweezing, enabled higher contrast and more detailed imaging, and offers a convenient way to harness the space degree of f...
Preprint
Full-text available
Quantum teleportation allows protected information exchange between distant parties, a crucial resource in future quantum networks. Using high-dimensional quantum states for teleportation offers the promise of higher information capacity channels, protection against optimal cloning machines and improved resilience to noise. However, such promising...
Article
Orbital angular momentum (OAM) modes are topical due to their versatility, and they have been used in several applications including free-space optical communication systems. The classification of OAM modes is a common requirement, and there are several methods available for this. One such method makes use of deep learning, specifically convolution...
Article
The high peak to average power ratio (PAPR) is the main challenge facing asymmetrically clipped optical (ACO) orthogonal frequency division multiplexing (OFDM). We propose a new hybrid technique that incorporates a modified selective mapping (SLM) and companding called low complexity hybrid selective mapping (LCHSLM) for PAPR mitigation in ACO OFDM...
Article
Free-space-optics-based communication links are an attractive potential solution for solving the last mile challenge but suffer from turbulence-induced fading. This fading causes errors in the received signal. While models exist to predict how turbulence affects the signal, these models often do not account for the channel's memory. Typical fading...
Article
Digital micro-mirror devices (DMDs) are a popular alternative to liquid crystal spatial light modulators for laser beam shaping due to their relatively low cost, high speed, and polarization and wavelength independence. Here we describe in detail how to convert a low-cost digital light projector (DLP) evaluation module that uses a Texas Instruments...
Article
A quantitative analysis of optical fields is essential, particularly when the light is structured in some desired manner, or when there is perhaps an undesired structure that must be corrected for. A ubiquitous procedure in the optical community is that of optical mode projections—a modal analysis of light—for the unveiling of amplitude and phase i...
Preprint
Full-text available
Optical communication is an integral part of the modern economy, having all but replaced electronic communication systems. Future growth in bandwidth appears to be on the horizon using structured light, encoding information into the spatial modes of light, and transmitting them down fibre and free-space, the latter crucial for addressing last mile...
Article
Full-text available
Free-Space Optical (FSO) systems offer the ability to distribute high speed digital links into remote and rural communities where terrain, installation cost or infrastructure security pose critical hurdles to deployment. A challenge in any point-to-point FSO system is initiating and maintaining optical alignment from the sender to the receiver. In...
Preprint
Full-text available
One of the major challenges for long range, high speed Free-Space Optical (FSO) communication is turbulence induced beam wander. Beam wander causes fluctuations in the received intensity as well as crosstalk in mode division multiplexed systems. Existing models for beam wander make use of probability distributions and long term averages and are not...
Article
Full-text available
Waves can carry both linear and angular momentum. When the wave is transverse (e.g. light), the angular momentum can be characterised by the “spin” angular momentum associated with circular polarisation, and the “orbital” angular momentum (OAM) arising from the phase cross-section of the beam. When the wave is longitudinal (e.g. sound) there is no...
Article
Full-text available
Higher bandwidth becomes a major challenge in the development and implementation of visible light communication systems as transmission rates increase. One way of increasing bandwidth is through wavelength division multiplexing in multicarrier systems that use red, green, and blue light‐emitting diodes to produce white light. However, these systems...
Conference Paper
Visible Light Communications (VLC) as well as Mode Division Multiplexing is a research area that is currently receiving significant interest which is beginning to migrate from proof-of-principle demonstrations towards optimized engineering. The ability to easily transmit and receive arbitrarily encoded and modulated optical signals is critical to p...
Preprint
Full-text available
The wavefront measurement of a light beam is a complex task, which often requires a series of spatially resolved intensity measurements. For instance, a detector array may be used to measure the local phase gradient in the transverse plane of the unknown laser beam. In most cases the resolution of the reconstructed wavefront is determined by the re...
Preprint
Full-text available
Vast geographical distances in Africa are a leading cause for the so-called "digital divide" due to the high cost of installing fibre. Free-Space Optical (FSO) communications offer a convenient and higher bandwidth alternative to point-to-point radio microwave links, with the possibility of re-purposing existing infrastructure. Unfortunately, the r...
Article
Full-text available
The wavefront measurement of a light beam is a complex task, which often requires a series of spatially resolved intensity measurements. For instance, a detector array may be used to measure the local phase gradient in the transverse plane of the unknown laser beam. In most cases, the resolution of the reconstructed wavefront is determined by the r...
Article
Innovations in ‘sustainable’ photonics technologies such as free-space optical links and solar-powered equipment provide developing countries with new cost-effective opportunities for deploying future-proof telecommunication networks.
Conference Paper
South Africa has one of the highest inequality factors in the world, reflecting its developed and developing nature. As such it suffers from the traditional “digital divide”, with low internet connectivity reach in rural areas, which is both economic and geographic in nature. In this talk we will summarize recent proposals to bridge the digital div...
Article
Full-text available
Vector vortex beams are structured states of light that are non-separable in their polarisation and spatial mode, they are eigenmodes of free-space and many fibre systems, and have the capacity to be used as a modal basis for both classical and quantum communication. Here we outline recent progress in our understanding of these modes, from their cr...
Article
Full-text available
The Large Hadron Collider at CERN generates enormous amounts of raw data which presents a serious computing challenge. After planned upgrades in 2022, the data output from the ATLAS Tile Calorimeter will increase by 200 times to over 40 Tb/s. Advanced and characteristically expensive Digital Signal Processors (DSPs) and Field Programmable Gate Arra...
Article
Full-text available
Modern big science projects are becoming highly data intensive to the point where offline processing of stored data is infeasible. High data throughput computing, or Data Stream Computing, for future projects is required to deal with terabytes of data per second which cannot be stored in long-term storage elements. Conventional data-centres based o...
Article
Full-text available
Big science projects are producing data at ever increases rates. Typical techniques involve storing the data to disk, after minor filtering, and then processing it in large computer farms. Data production has reached a point where on-line processing is required in order to filter the data down to manageable sizes. A potential solution involves usin...
Conference Paper
Full-text available
Scientific experiments are becoming highly data intensive to the point where offline processing of stored data is infeasible. High data throughput computing or High Volume throughput Computing, for future projects is required to deal with terabytes of data per second. Conventional data-centres based on typical server-grade hardware are expensive an...
Article
Full-text available
After Phase-II upgrades in 2022, the data output from the LHC ATLAS Tile Calorimeter will increase significantly. ARM processors are common in mobile devices due to their low cost, low energy consumption and high performance. It is proposed that a cost-effective, high data throughput Processing Unit (PU) can be developed by using several consumer A...

Network

Cited By

Projects

Projects (2)
Project
Increase the capacity and robustness of free space optical communications.