A prism splitting light. Scientists have slowed light to a fraction of its usual speed using optical fibres.
Credit: NASA
SYDNEY: Light has been slowed to a fraction of its speed using optical fibres which may soon replace coventional electronics used for the Internet, Australian researchers say.
"Slow light is the hot topic in modern physics," said Ben Eggleton of Sydney University, leader of the research team who published their study in the British journal Nature Physics. "It is both fundamental research and an important technological breakthrough."
Light is usually the fastest thing in our universe, able to travel to the moon and back in less than four seconds. But not in the physics labs at Sydney University, where it is forced to travel at around 16 per cent of its normal speed.
More critically, as the pulse of light is slowed it doesn't change its shape, an important feature that was achieved only after overcoming basic physical principles.
This breakthrough has the potential to unleash a much faster Internet.
Through the Internet, people at opposite sides of the globe are able to exchange information in the form of light. However all the switches and routers - the devices that direct information to its intended place - are still electronic.
This means that light pulses are converted into electric signals, and then converted back into light. According to Eggleton, these electronic devices are far too slow and inefficient - consuming too much energy through the banks of air conditioners required to keep them cool.
He envisions future networks that use only optical devices: by slowing light to a fraction of its normal speed, it becomes possible to hold and release batches of information while they are still in the form of light.
"All-optical solutions … are intrinsically faster, 100 times faster, and will ultimately replace the electronic processing," he said. "We expect to see all-optical solutions in the next five to 10 years."
Over the past seven years, a number of physicists around the world have managed to create systems that slow down light to a leisurely, human pace. Until now, however, the light pulses have always ripped themselves apart as they slowed down.
In this study, the researchers used a common type of optical fibre in a not-so common way. They realised that when very bright light was shone through the optical fibre, the light would take on unusual properties.
In their system, as the light pulse tries to rip itself apart it is perfectly counterbalanced by this bizarre interaction with the optical fibre. What they created was a special kind of wave that can travel long distances without changing.
This type of wave was, oddly enough, first observed in a Scottish ship canal in 1834. An engineer was watching a boat being pulled along a canal. The boat stopped, and a mass of water built up in front of it. The water then rolled forward, leaving the boat behind, and continued as a solitary wave for kilometres without breaking up, crumbling or toppling over like most waves.
The shape of the canal was just right to create a 'self-reinforcing single wave' - or soliton.
A number of physicists working with slow light have been trying to overcome the problem of light ripping itself apart. Eggleton and his team are the first to show they can create slow light that propagates as solitons.
"We believe we can turn this early fundamental discovery into a practical device that will bring ultra-fast Internet - and opportunities for Australian companies to jump on the next wave of the Internet revolution," said Eggleton.
