The new microchip design uses sound waves on the surface for advanced sensing technology.

A team of researchers has successfully used lasers to generate targeted sound waves on the surface of a microchip for the first time. These acoustic waves, similar to the surface waves produced during an earthquake, propagate across the chip at frequencies nearly a billion times higher than those found in earthquakes.

By trapping the sound wave on the surface of the chip, it can more easily interact with its environment, making it an ideal candidate for advanced sensor technologies.

The results were published in APL Photonics.

“The use of sound waves on the surface of a microchip has applications in sensing, signal processing and advanced communications technologies,” said senior author and project leader Dr Moritz Märklein from the Nano Institute and School of Physics at the University of Sydney. “We can now start thinking about new chip designs that use light and sound instead of electricity.

Lead author Govert Neates, a student at the University of Twente in the Netherlands who spent nine months in laboratories at the University of Sydney, said: “Normally, surface acoustic waves are ‘excited’ electronically. Here we use photonics, or light energy, to create a sound wave. This approach has many advantages, the main one being that the light does not generate heat in the chip, which causes electronic excitation.”

Using a special glass made of germanium, arsenic and selenide, known as GeAsSe, the scientists were able to achieve remarkable results, including measurements indicating a strong interaction between light and sound.

This innovative research demonstrates how lasers can be used to create and detect high-frequency surface acoustic waves using new materials as a “waveguide.”

“This material is considered soft glass. This means that, unlike many materials, it acts as a conductor for high-frequency sound waves and allows them to interact more freely with the light waves we put on the chip,” said Dr. Merklein. .

The ability to generate and manipulate these high-frequency acoustic waves opens up a world of possibilities for new applications in sensing and signal processing.

Co-author Dr Chun-Kong Lai, a research fellow at the Institute of Photonics and Optical Sciences at the University of Sydney, said: “Imagine sensors that can detect minute changes in the environment, or advanced signal processing techniques that improve communications technology.

“Our innovative approach not only paves the way for more sensitive and efficient devices, but also expands the ability to integrate acoustic and optical technologies on a single chip.”

The team previously demonstrated “capturing” light information within phononics, or sound waves, within a chip. This innovation of “lightning within thunder” was a world first at that time.

“We designed this work to be able to control and direct high-frequency sound wave information onto the surface of the chip. This is an important contribution to the development of new sensing technologies,” said co-author and leader of the research group, Professor. Ben Eggleton, Vice-Chancellor (Research), University of Sydney.

The method used by the researchers is known as stimulated Brillouin scattering (SBS). This is created by an extended feedback loop between photons (light) and phonons (sound).

When light moves around a chip or optical fiber, it creates sound vibrations. This was previously considered an interference in optical communications, but then scientists realized that they could combine and amplify this vibration as a new way of transmitting and processing information.

The feedback process allows light waves (usually created by lasers) and sound waves to “interlock”, increasing the strength of this feedback effect. Researchers expect stimulated Brillouin scattering to find applications in 5G/6G and broadband networks, sensors, satellite communications, radar systems, defense systems and even radio astronomy.