Dr Birgit Still (left) and Moritz Merklein at the University of Sydney Nanoscience Hub. Photo: Louise Connor

World-first transfer of light to acoustic information on a chip

Acoustic buffer parks information in a sound wave for later retrieval

Researchers at the University of Sydney have dramatically slowed digital information carried as light waves by transferring the data into sound waves in an integrated circuit, or microchip.

It is the first time this has been achieved.

Transferring information from the optical to acoustic domain and back again inside a chip is critical for the development of photonic integrated circuits: microchips that use light instead of electrons to manage data.

These chips are being developed for use in telecommunications, optical fibre networks and cloud computing data centres where traditional electronic devices are susceptible to electromagnetic interference, produce too much heat or use too much energy.

“The information in our chip in acoustic form travels at a velocity five orders of magnitude slower than in the optical domain,” said Dr Birgit Stiller, research fellow at the University of Sydney and supervisor of the project.

“It is like the difference between thunder and lightning,” she said.

This delay allows for the data to be briefly stored and managed inside the chip for processing, retrieval and further transmission as light waves.

Light is an excellent carrier of information and is useful for taking data over long distances between continents through fibre-optic cables.

But this speed advantage can become a nuisance when information is being processed in computers and telecommunication systems.

To help solve these problems, lead authors Moritz Merklein and Dr Stiller, both from the ARC Centre of Excellence for Ultrahigh bandwidth Devices for Optical Systems (CUDOS) have now demonstrated a memory for digital information that coherently transfers between light and sound waves on a photonic microchip.

The chip was fabricated at the Australian National University’s Laser Physics Centre, also part of the CUDOS Centre of Excellence.

Their research was published on Monday in Nature Communications.