Integrated photonic devices—tiny circuits that use light instead of electrons—are becoming increasingly important for scalable photonics technologies and high-bandwidth communications. They are particularly valuable for managing low-power, light-based data transfer inside data centers, which are needed for artificial intelligence, cloud computing and high-performance signal processing.

A major challenge for the field is developing approaches that force light to propagate in only one direction within a photonic circuit, since this can improve robustness to manufacturing defects, protect laser sources and impart greater stability to optical signals within the system.

Researchers at the University of Illinois Urbana-Champaign’s Grainger College of Engineering have developed a photonic integrated circuit that functions as a linear optical isolator, allowing light to pass in only one direction with extremely low loss while blocking almost all light propagating in the opposite direction. The results are published in Nature Communications.