Researchers demonstrate a 100x increase in the amount of information that can be 'packed into light'

Light: Information's new friend
Data of the Rubik's cube sent and received. Credit: Wits University

The rise of big data and advances in information technology has serious implications for our ability to deliver sufficient bandwidth to meet the growing demand.

Researchers at the University of the Witwatersrand in Johannesburg, South Africa, and the Council for Scientific and Industrial Research (CSIR) are looking at alternative sources that will be able to take over where traditional optical communications systems are likely to fail in future.

In their latest research, published online today (10 June 2016) in the scientific journal, Scientific Reports, the team from South Africa and Tunisia demonstrate over 100 patterns of used in an optical communication link, potentially increasing the of by 100 times.

The idea was conceived by Professor Andrew Forbes from Wits University, who led the collaboration. The key experiment was performed by Dr Carmelo Rosales-Guzman, a Research Fellow in the Structured Light group in the Wits School of Physics, and Dr Angela Dudley of the CSIR, an honorary academic at Wits.

The first experiments on the topic were carried out by Abderrahmen Trichili of Sup'Com (Tunisia) as a visiting student to South Africa as part of an African Laser Centre funded research project. The other team members included Bienvenu Ndagano (Wits), Dr Amine Ben Salem (Sup'Com) and Professor Mourad Zghal (Sup'Com), all of who contributed significantly to the work.

Bracing for the bandwidth ceiling

Traditional optical communication systems modulate the amplitude, phase, polarisation, colour and frequency of the light that is transmitted. Yet despite these technologies, we are predicted to reach a bandwidth ceiling in the near future.

Light: Information's new friend
Dr. Carmelo Rosales-Guzman from Wits University. Credit: Wits University

But light also has a "pattern" - the intensity distribution of the light, that is, how it looks on a camera or a screen.

Since these patterns are unique, they can be used to encode information:

  • pattern 1 = channel 1 or the letter A,
  • pattern 2 = channel 2 or the letter B, and so on.

What does this mean?

That future bandwidth can be increased by precisely the number of patterns of light we are able to use.

Ten patterns mean a 10x increase in existing bandwidth, as 10 new channels would emerge for data transfer.

At the moment modern systems only use one pattern. This is due to technical hurdles in how to pack information into these patterns of light, and how to get the information back out again.

How the research was done

In this latest work, the team showed data transmission with over 100 patterns of light, exploiting three degrees of freedom in the process.

They used digital holograms written to a small liquid crystal display (LCD) and showed that it is possible to have a hologram encoded with over 100 patterns in multiple colours.

Researchers demonstrate a 100x (times) increase in the amount of information that can be "packed into light" by showing how information was encoded into patterns of light by "sending" and "receiving" this example of a Rubik's cube. Credit: Wits University
"This is the highest number of created and detected on such a device to date, far exceeding the previous state-of-the-art," says Forbes.

One of the novel steps was to make the device 'colour blind', so the same holograms can be used to encode many wavelengths.

According to Rosales-Guzman to make this work "100 holograms were combined into a single, complex hologram. Moreover, each sub-hologram was individually tailored to correct for any optical aberrations due to the colour difference, angular offset and so on".

What's next?

The next stage is to move out of the laboratory and demonstrate the technology in a real-world system.

"We are presently working with a commercial entity to test in just such an environment," says Forbes. The approach of the team could be used in both free-space and optical fibre networks.


Explore further

Laser beams with a 'twist'

More information: Scientific Reports, http://www.nature.com/articles/srep27674
Journal information: Scientific Reports

Provided by Wits University
Citation: Researchers demonstrate a 100x increase in the amount of information that can be 'packed into light' (2016, June 10) retrieved 25 April 2019 from https://phys.org/news/2016-06-100x-amount.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
1316 shares

Feedback to editors

User comments

Jun 10, 2016
'Pattern' does not compute as light property.

Jun 10, 2016
Read the article in Nature. Makes more sense.

Jun 10, 2016
modulate the amplitude, phase, polarisation, colour and frequency

colour AND frequency? Separately? Really?

(Not knocking the researchers. The work will certainly find its way into real-world applications quickly)

Jun 10, 2016
heheh... and brightness and amplitude

Jun 10, 2016

colour AND frequency? Separately? Really?


Since the articles are truncated, maybe frequency is referring to baud rate rather than the light's wavelength.

I am hypothesizing not telling.

Jun 13, 2016
Pretty sure this is the preprint: http://arxiv.org/...94v1.pdf

Science is giving HTTP 500 errors just at the moment; I will check later if it's the same article. But it sure looks that way.

Jun 13, 2016
Isn't all wireless comprised of photons? Would they not also be amenable to these methods?

Anybody know Dr. Carmelo Rosales-Guzman's origin story?

Jun 13, 2016
Isn't all wireless comprised of photons? Would they not also be amenable to these methods?
Good question, but no. The reason is because the wavelength of EM radiation gets bigger as the energy per photon gets bigger; this means it falls off very quickly. There's quite a high power density in a laser beam, many orders of magnitude higher than in a UHF signal, and the UHF signal isn't nearly as coherent. Almost all of the laser beam hits the target; the UHF spreads out a lot. The front-to-back ratio of a really good UHF antenna is on the close order of 15; the front-to-back ratio of a laser is on the order of 100,000. And that's leaving aside wavelength.

Jun 14, 2016
Pretty sure this is the preprint: ...f
It is

Jun 14, 2016
Bah, screwed that one up: the wavelength gets bigger as the energy per photon gets *smaller*. The rest is all correct.

Jun 14, 2016
Isn't all wireless comprised of photons? Would they not also be amenable to these methods?


Good question, but no.


Just to clarify: yes: wireless is composed of photons. (And no: it's not applicable to wireless because of what DaSchneib said)

That said, if I read the paper right, it seems the method only works if there is a direct line of sight (or if the optic fiber is straight) because it uses a spatial distribution that has to be just so before the DeMux stage.

Jun 14, 2016
... it seems the method only works if there is a direct line of sight (or if the optic fiber is straight) because it uses a spatial distribution that has to be just so before the DeMux stage..
Probably very impacted by things like the wavefront angle of incidence at the receiver and beam divergence, Should be OK using fiber, but free-air would need to be pretty controlled (optical bench)

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more