Physicists at the Australian National University (ANU) have developed new technology that will determine the direction in which light can and cannot travel using nanoparticles, potentially discovering the path to cheaper, faster and more reliable internet†
Working with colleagues from Singapore, China and Germany, ANU scientists have developed small translucent slides that produce two different images depending on the direction in which the light travels through them. For example, at first a slide may produce an image from a microscope, but once flipped it creates an image of a collection of wheels and gears, and this is just one of many possibilities.
“The particles control the flow of light like road signs direct traffic on a busy road by manipulating the direction in which light can or cannot travel,” said project leader Sergey Kruk of ANU’s Nonlinear Physics Center in an ANU press release†
“Some particles only allow light to flow from left to right, others from right to left, or the path can be blocked in both directions.”
“While the purpose of these images is primarily artistic, they demonstrate the potential of this new technology,” said Lei Wang of Southeast University in China.
“In real-world applications, these nanoparticles can be assembled into complex systems that usefully control light flux, such as in next-generation communications infrastructure,” Wang said.
What this technology means for future technology
The researchers note that the breakthrough has the potential to create new light-based devices that could hold not only the key to improved and cheaper internet, but also the foundation for multiple technologies of the future.
Kruk said controlling light flux at the nanoscale guarantees light goes where it needs to go and avoids where it isn’t.
“We exchange enormous amounts of information using light,” he said. “If you have a video call, for example from Australia to Europe, your voice and image are converted into short pulses of light that travel thousands of kilometers through an optical fiber across the continents and oceans.”
“Unfortunately, if we use current light-based technologies to exchange information, many parasitic effects can occur. Light can be scattered or reflected, endangering your communication.”
Kruk said many problems with current technologies would be solved if the light was guaranteed to flow exactly where it was supposed to.
“In general, the traffic control of nanoscale light that we are working on resembles the traffic control of electric currents in our computer chips (performed with semiconductor diodes and nanoscale transistors).”
“If information is processed with light rays instead of electric currents, certain tasks can be performed much faster.”
He said the widespread deployment of small technology that controls the flow of light could lead to technological and social changes reminiscent of those caused by diodes and transistors — small components that control the flow of electricity.
“Controlling the flow of electricity at the nanoscale is what ultimately brought us modern computers and smartphones. It is therefore exciting to imagine the potential of our emerging technology for controlling the flux of light.”
Rival Technology
“A useful device for optical communication is an ‘optical isolator,'” Kruk said in an email to The Epoch Times. “It allows light to propagate forward, but not backward, protecting advanced communication systems from parasitic backward scattering and reflections.”
Although optical isolators, like the new technology developed by ANU, can control the luminous flux, they have drawbacks.
“Current optical isolators are quite large and expensive. Commercial insulators that we buy for our lab are usually several inches in size and cost over $1,000,” he said.
“This line of research can reduce the size of optical isolators to the nanoscale (nanometer — one billionth of a meter) and also reduce costs to a fraction of a dollar.
“A broad deployment of small and inexpensive optical isolators would facilitate the development of faster, more reliable and cheaper internet.”
According to Kruk, however, there is currently an important difference between the newly developed slides and the optical isolators.
“Our slides change the color of light, or in other words, the frequency at which the light wave oscillates, whereas an optical isolator does not.”
Plans to tackle the device that changes the light color
Kruk said that nonlinear optics — how materials interact with very bright rays of light, such as lasers — are the fundamental physical principle that allows for asymmetry in the way light interacts with the translucent slide.
“In this work, we used a nonlinear optical phenomenon called ‘third harmonic generation’ that triples the frequency of light.”
He said the team is currently working on applying a second optical phenomenon called “nonlinear self-action,” which will preserve the asymmetric transmission of light while preserving its frequency.
“For the first step, we chose ‘third harmonic generation’ because it works well with silicon – one of the easiest materials for nanofabrication (computer chips are made of silicon, therefore nanofabrication techniques are very mature).”
“For the second step based on ‘self-action’ (eg no frequency change), we are investigating different, somewhat more exotic materials, and high-quality nanofabrication is one of the challenges.”
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Lily Kelly is an Australian reporter for The Epoch Times, covering social issues, renewable energy, the environment and health and science.