Frequently Asked Questions

Two FBGs spaced along the same fiber form a cavity between them, similar to a conventional Fabry-Perot interferometer's mirrors. Small phase shifts inside that cavity — from temperature, strain, or acoustic waves — become detectable through changes in the cavity's transmission spectrum.

Beyond temperature and strain, coating the fiber between the two gratings with an electric-, magnetic-, or acoustic-sensitive material lets the cavity detect small changes in those fields as well.

No — for many sensing tasks, including vibration and acoustic signal detection via an interferometric method, a low-finesse Fabry-Perot cavity is sufficient.