Studying waves over astronomical distances

Jul 08, 2013

Tiny pulses of light one billionth of a second apart, travelling further than from the Earth to Sun, were used in an exquisitely sensitive experiment at The University of Auckland to explore fundamental interactions between light and sound.

The research, led by Associate Professor Stéphane Coen from the Department of Physics, examined the behaviour of solitons.

Solitons are which maintain their shape in contrast, for instance, to waves hitting the shore which break and fragment. They are found in a wide range of situations, and learning more about them will help physicists understand many phenomena in the natural world.

Solitons were first seen in shipping canals, in which a boat coming to a sudden stop gave rise to a single large propagating wave. They also describe tsunamis – waves which travel unabated across entire oceans – and appear in both scorching hot plasmas and ultracold gases.

In addition, solitons exist in microscopic glass rings, new devices used by scientists to generate frequency combs. These are a type of light source used to make extremely and which underpinned a Nobel Prize in 2005.

The University of Auckland work examined how two solitons in the same system affect one another. It reports the weakest interaction ever measured between solitons, and has been published in the journal Nature Photonics.

"This was beautifully sensitive work, and tests our understanding of the of nature," says Head of Department of Physics Professor Richard Easther.

The experiment was done using a loop of fibre . Two pulses (solitons) of were fired into the loop one billionth of a second apart, and allowed to continue travelling until one was found to have an influence on the other.

It wasn't until the pulses had travelled 150 million kilometres – the distance from the Earth to the Sun – that an effect was observed. The gap separating the pulses changed by a billionth of a billionth of a second for every roundtrip in the 100 metre-long loop.

As it travelled, the first pulse created an ultrasound wave in the fibre that disturbed the path of the second, detected as a change in its velocity. The effect was so tiny that it could only be observed after the pulses had travelled astronomical distances.

This was the first time an experimental apparatus had been built that allowed such weak interactions to occur and to be observed.

The work was done by University of Auckland physicists Associate Professor Stéphane Coen, Dr Stuart Murdoch, Dr Miro Erkintalo, and PhD student Jae Jang. It was supported by a Marsden grant of The Royal Society of New Zealand awarded to Associate Professor Coen and colleagues in 2011.

The paper, titled "Ultra-weak long-range interactions of solitons observed over astronomical distances" has been published online ahead of print on the Nature Photonics website.

The researchers are now looking to extend this work, and take advantage of their new understanding to facilitate the use of solitons in communications applications.

Explore further: Researchers seek broadband/multiband electromagnetic absorbers based on plasmonic and metamaterial structures

More information: Ultra-weak long-range interactions of solitons observed over astronomical distances, DOI: 10.1038/nphoton.2013.157

Related Stories

Solitary waves induce waveguide that can split light beams

Mar 15, 2012

Researchers have designed the first theoretical model that describes the occurrence of multiple solitary optical waves, referred to as dark photovoltaic spatial solitons. The findings by Yuhong Zhang, a physicist from the ...

Physicists create nanoscale spinning magnetic droplets

Mar 14, 2013

Researchers have successfully created a magnetic soliton – a nano-sized, spinning droplet that was first theorized 35 years ago. These solitons have implications for the creation of magnetic, spin-based computers.

Finding the right soliton for future networks

May 14, 2008

European researchers say their study of self-sustaining solitary light wave packets could result in a new generation of computers and optical telecommunications networks. Using light rather than electronic or magnetic devices ...

Recommended for you

Study finds physical link to strange electronic behavior

10 hours ago

Scientists have new clues this week about one of the baffling electronic properties of the iron-based high-temperature superconductor barium iron nickel arsenide. A Rice University-led team of U.S., German ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

El_Nose
not rated yet Jul 08, 2013
this might be a silly question -- but would this effect redshifted EM waves that are used to determine distances of objects in space.
Q-Star
1 / 5 (2) Jul 08, 2013
this might be a silly question -- but would this effect redshifted EM waves that are used to determine distances of objects in space.


Not really. It is an entirely different phenomena. Redshift is a manifestation of the relative velocities of the source and observer. The speed of light is not changing, the separation is the thing that is changing giving rise to cosmological redshift. The other redshift that is used in astrophysics (redshift due to motion or due to gravitational fields) wouldn't be affected for the same reason.