Scientists have developed a dual-laser Brillouin optical correlation-domain reflectometry (BOCDR) system that uses two frequency-modulated lasers. By scanning the relative modulation phase between the pump and reference lasers, the setup measures strain and temperature all along an optical fiber. In a proof-of-concept test on a 13-meter silica fiber, the team recorded Brillouin gain spectra (BGS) at only about 200 MHz—over 50 times lower than the usual 11 GHz band.

The research was published in the Journal of Physics: Photonics on April 25, 2025.

“The dual-laser approach makes BOCDR equipment simpler, more cost-effective, and easier to deploy, giving engineers a practical tool for long-term structural health monitoring, factory process control, and many other sensing tasks,” said senior author Associate Professor Yosuke Mizuno of Yokohama National University.