Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Light in a spin

16.04.2015

Researchers demonstrate angular accelerating light

Light must travel in a straight line and at a constant speed, or so the laws of nature suggest. Now, researchers at the University of the Witwatersrand in Johannesburg have demonstrated that laser light traveling along a helical path through space, can accelerate and decelerate as it spins into the distance.


Researchers at the University of the Witwatersrand in Johannesburg have demonstrated that laser light traveling along a helical path through space, can accelerate and decelerate as it spins into the distance. Here the light is accelerating.

Credit: Andrew Forbes/Wits University

This is the first time that angular acceleration has been observed with light, and is therefore likely to lead to new applications using these structured light fields.

The results are contained in a research paper by Professor Andrew Forbes from the Wits School of Physics and his collaborators¹, published online this week in the journal, Physical Review A. Titled: Accelerated rotation with orbital angular momentum modes, the work has also been selected as a highlighted paper by the editors.

Forbes, who joined the Wits School of Physics in March this year, is heading up the new Structured Light Laboratory that focuses on creating custom light fields using digital holograms. The research group creates complex light that exhibits interesting physical properties, which they exploit for a range of applications.

Previously, Forbes and his collaborators have shown that light could be made to spin. In this recent work they demonstrated the first realisation of angular accelerating light and showed that light could also be made to accelerate and decelerate. This acceleration can be controlled with a single parameter that is readily tuned with a digital hologram written to a standard LCD screen, much like your LCD television at home, but just a much smaller version.

"Our angular accelerating fields rely on combinations of orbital angular momentum - so-called twisted light," says Forbes. Light carrying orbital angular momentum is created by twisting the wave-front of light into a helical shape, forming a spiral. Usually this twist in the light's wave-front is smooth, like a spiral staircase with regular steps. "Our novelty was to realise that by twisting the helicity of these beams in a non-linear fashion, the result would be a propagation dependent angular velocity," he explains. In other words, the light spins at a non-constant speed, resulting in angular acceleration.

In fact, the light speeds up and slows down as it travels, periodically switching from one mode to the other. Following its helical path through space, the helix appears to wind up very tightly as it accelerates, and winds down very loosely as it decelerates. It is intriguing that by "twisting the twist", nature provides an additional momentum to the field causing it to accelerate as it spins.

The team expects this new optical field to be of interest as a tool to study some fundamental physical processes with light, as well as a tool in optically driving micro-fluidic flow.

###

¹The idea was conceived by Forbes who led the collaboration with Christian Schulze and Michael Duparré (University of Jena, Germany), Ronald Rop (Eggerton University, Kenya), and Filippus Roux and Angela Dudley (Council for Scientific and Industrial Research, South Africa).

Media Contact

Erna van Wyk
erna.vanwyk@wits.ac.za
27-117-174-023

 @witsuniversity

http://www.wits.ac.za 

Erna van Wyk | EurekAlert!

More articles from Physics and Astronomy:

nachricht The dispute about the origins of terahertz photoresponse in graphene results in a draw
25.04.2018 | Moscow Institute of Physics and Technology

nachricht Structured light and nanomaterials open new ways to tailor light at the nanoscale
23.04.2018 | Academy of Finland

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

The dispute about the origins of terahertz photoresponse in graphene results in a draw

25.04.2018 | Physics and Astronomy

Graphene origami as a mechanically tunable plasmonic structure for infrared detection

25.04.2018 | Materials Sciences

First form of therapy for childhood dementia CLN2 developed

25.04.2018 | Studies and Analyses

VideoLinks
Science & Research
Overview of more VideoLinks >>>