Extending the life of acoustic waves on microchips

Scientists from the University of Sydney and the Max Planck Institute for the Science of Light have taken an important step towards removing electrons from the data chips that are a driving force in global telecommunications, which should allow for the invention of data processing systems that don’t overheat, have low energy costs and reduce greenhouse gas emissions.

Their work was published in the journal Optica and conducted in collaboration with the Australian National University (ANU) and the University of Southern Denmark.

The researchers say that chips using light and sound, rather than electricity, will be important for the development of future tech, such as high-speed internet as well as radar and sensor technology. This will require the low-heat, fast transmission of information, using soundwaves known as phonons to store and transfer information that chips receive from fibre-optic cables. This allows the chips to operate without needing electrons, which produce heat.

Back in 2017, the Sydney researchers were reportedly the first in the world to successfully manage this process on-chip. However, information transferred from fibre-optic cables onto chips in the form of soundwaves decays in nanoseconds, which is not long enough to do anything useful.

“What we have done is use carefully timed synchronised pulses of light to reinforce the soundwaves on-chip,” said Dr Birgit Stiller, who has moved from the University of Sydney to the Max Planck Institute for the Science of Light.

“We have shown for the first time that refreshing these phonons is possible and that information can therefore be stored and processed for a much longer time.”

The scientists carefully timed pulses of light to extend the lifetime of the information stored in soundwaves on the chip by 300%, from 10 to 40 ns. This proof-of-principle demonstration opens many possibilities for optical signal processing, fine filtering, high-precision sensing and telecommunications.

“We plan to use this method to extend how long the information remains on-chip,” said Dr Moritz Merklein from the University of Sydney. Associate Professor Christian Wolff, a project collaborator from the University of Southern Denmark, added, “Theoretically, this concept can be extended to the microsecond regime.”

Dr Stiller concluded, “Acoustic waves on chips are a promising way to store and transfer information.

“So far, such storage was fundamentally limited by the lifetime of the soundwaves. Refreshing the acoustic waves allows us to overcome this constraint.”

Image caption: Dr Birgit Stiller and Dr Moritz Merklein in the Sydney Nanoscience Hub, University of Sydney.

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