Researchers at McGill University, Ciena and HyperLight have tested a chip-scale light router in a two-way fibre link spanning 40 kilometres. Their September 11 Nature Photonics paper describes a device built without the magnetic materials used in conventional optical circulators.
A circulator directs outgoing light into the fibre and incoming light toward the receiver, keeping reflections away from the laser. Integrating this function into chips could reduce the bulky components used at each end of a link.
The new device uses lithium niobate, a material whose optical properties change with voltage. Electrical signals act on two successive light-control sections. Their timing makes light interfere differently depending on its direction, suppressing the route back to the transmitter while preserving the receiving route.
Tests used 20- and 40-kilometre fibres, with the prototype at one end and a conventional circulator at the other. The prototype handled one polarization, the orientation of light's electric field. Supporting both polarizations used by standard high-capacity transceivers would require additional circuitry.
Sources
- Charles St-Arnault and colleagues, Nature Photonics, September 11, 2026. DOI: 10.1038/s41566-026-02008-9.
- Authors' simulation code and figure data.
- Illustrative file photograph: Asurnipal, optical fibre splice box, December 3, 2019; CC BY-SA 4.0. Displayed at reduced size, with no crop or other changes; not the experimental device.
