By Isabelle Robinson, M.Sc.Nov 2 2018.jpg)
Image Credits: ioat/shutterstock.com
In September 2017, a team of researchers from Australia revealed that, for the first time, they were able to turn light into sound on a microchip.
The importance of this achievement cannot be underestimated. The ability to make photons process information like electrons on a computer has been a widely researched field and could mean that computers use less energy and produce less heat than traditional computers. These photonic computers could run up to 20 times faster than a laptop. However, this is no simple task due to the speed at which photons travel. In order to be able to achieve this task, researchers needed to find a way to slow them down.
It is known that light and sounds both travel as waves. Light travels as radiation waves and is able to move through a vacuum, while sounds travel as vibrational waves through the air. The smallest unit of sound is known as a phonon while a unit of light is called a photon. It is this similarity that has allowed scientists to turn light into sound.
The new microchip uses the stimulated Brillouin scattering to convert light into sound. The research team from the University of Sydney used two light waves, one of which containing the data, and passed the waves through a wire that helped guide the photons. When the two waves collided, the information within the light wave’s electrical field excited the material around it and therefore created a sound wave. The researchers were able to reverse this process with a sound wave, creating the original light wave pulse.
The information in our chip in acoustic form travels at a velocity five orders of magnitude slower than in the optical domain. It is like the difference between thunder and lightning.
Birgit Stiller, Project Supervisor, University of Sydney
The team’s microchip light-to-sound converter is the size of a small coin, with the guiding wire being only one micrometer thick and ten centimeters in length. While the velocity was certainly slowed down the signal still only lasted approximately 3.5 nanoseconds. In addition to this, according to their research paper, the chip isn’t perfectly efficient, sometimes losing some of the information.
"For photonic computers to become a commercial reality, photonic data on the chip needs to be slowed down so that they can be processed, routed, stored and accessed," said Moritz Merklein, a researcher at the University of Sydney.
"This is an important step forward in the field of optical information processing as this concept fulfills all requirements for current and future generation optical communication systems," added Benjamin Eggleton, another member of the research team.
The research is the beginning stage in a very important step towards more efficient photonic computers. In addition to this, unlike all the previous attempts, the research team was able to make the system work across a broad bandwidth.
Our system is not limited to a narrow bandwidth. So unlike previous systems, this allows us to store and retrieve information at multiple wavelengths simultaneously, vastly increasing the efficiency of the device.
Birgit Stiller, Project Supervisor, University of Sydney
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