Recently, researchers have successfully used a laser to generate guided sound waves on the surface of a microchip for the first time. These sound waves are similar to seismic surface waves, but propagate nearly a billion times more frequently on the chip than the Earth's motion. Since the sound waves are confined to the surface of the chip, they can better interact with the surrounding environment, making it have great potential in advanced sensing technology. The findings have been published in the journal Photonics of the United States Physical Society.
The project, led by Dr Moritz Merklein from the University of Sydney's Institute of Nanotechnology and School of Physics, noted: "The application of sound waves on the surface of microchips is helping to advance sensing, signal processing and advanced communication technologies. Instead of relying on electricity, we can begin to design new types of chips based on light and sound.”
Lead author Govert Neijts, from the University of Twente in Netherlands and working in a laboratory at the University of Sydney for nine months, explains: "Normally surface sound waves are generated by electron excitation, but we use photonics or light energy to generate sound waves. The main advantage is that light does not generate heat in the chip as electron excitation does.”
The research team used a special glass material, GeAsSe glass composed of germanium, arsenic, and selenium, which exhibits strong photoacoustic interactions, and achieved important results. This groundbreaking study demonstrates that lasers can harness new materials to create and detect high-frequency surface sound waves.
Figure: For the first time, researchers are using a laser to generate guided acoustic waves on the surface of a microchip
Dr. Merklein added: "GeAsSe is considered a soft glass, which means that it acts as a guide for high-frequency sound waves and allows these sound waves to interact freely with the light waves in the chip.”
By successfully generating and manipulating these high-frequency sound waves, research opens up new possibilities for sensing and signal processing. Dr Choon-Kong Lai, from the Institute of Photonics and Optical Sciences at the University of Sydney, said: "This innovation is expected to enable sensors to detect even the most subtle changes in the environment and drive more advanced signal processing techniques to significantly improve communication performance. This not only paves the way for more sensitive and efficient devices, but also expands the potential of integrating acoustic and optical technologies on a single chip.”
Previously, the team showed how to "capture" the light information carried in sound waves or phonons, an innovation known as "lightning in thunder" and a world first at the time.
Professor Ben Eggleton, Vice-Chancellor and Vice-Chancellor of the University of Sydney, also said: "We have further developed this technology and are now able to manage and direct high-frequency acoustic information on the surface of the chip, which is a significant contribution to the development of new sensing technologies.”
The technique employed by the researchers is called stimulated Brillouin scattering (SBS), which utilizes an enhanced feedback loop between photons and phonons. When light travels around a chip or optical fiber, it creates acoustic vibrations. Although this phenomenon was once seen as a problem in optical communications, scientists have found that it can actually be coupled and enhanced as a new way of transmitting and processing information.
Through the feedback process, the light and sound waves generated by the laser can be coupled and enhance the feedback effect. The researchers expect this stimulated Brillouin scattering technique to be used in 5G/6G, broadband networks, sensors, satellite communications, radar systems, defense systems, and even radio astronomy.
