Chips and electronic devices have become smaller and faster over the years. Engineers are in the process of transitioning from electronics to photonics, using light instead of electrons. There are a lot of new challenges at this level. The smallest interferences can make signals useless. A research team from the University of Twente have created a new solution to the problem.
The development of new telecommunication techniques is dependent on the processing of optical signals. The stimulated Brillouin scattering technique is one way to do this effectively. The sound wave frequencies are 1 million times higher than the human hearing threshold and are generated by two lasers. A small part of the light spectrum will be reflected by the sound wave, which filters out the rest of the signal.
Even though Brillouin scattering has been studied extensively in the last few years, it could never be implemented reliably on a chip. It has proven to be very difficult to trap the sound wave in a waveguide. Strong Brillouin interactions are prevented in traditional Silicon-based platforms. Alternative materials are not always stable or safe.
There is a breakthrough with a chip.
The research team at the University of Twente has been using low-loss Silicon nitride to confine both the optical and acoustic waves. The circuits have 50 cm-long spirals. When using a single core, this setup traps the sound wave and prevents the acoustic leak. A proof of concept and other practical implementations were produced by the researchers. The results of the experiment show a great potential for stimulated Brillouin scattering on a chip.
Integration of Brillouin scattering in large circuits can be achieved thanks to our research. These new chips can be integrated with other emerging technologies, potentially giving them a role in the future development of fields such as telecommunications to quantum computing.
The feasibility of stimulated Brillouin scattering was studied for four years in a research paper published in October. The MESA+ institute at the University of Twente was the location of the research. LioniX International is a spin-off of the University of Twente and produces the chips.
More information: Roel Botter et al, Guided-acoustic stimulated Brillouin scattering in silicon nitride photonic circuits, Science Advances (2022). DOI: 10.1126/sciadv.abq2196 Journal information: Science Advances
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