Distributed Hydrogen Sensing With Brillouin Scattering in Optical Fibers

We report on the design and test of a truly distributed hydrogen sensor based on Brillouin scattering into single-mode G652 optical fibers. The proposed system enables remote, robust, long-term, and truly distributed hydrogen sensing into long-range structures, such as radioactive waste repositories, with a spatial resolution in the order of 2 m over several hundred meters. For the first time, we demonstrate that Brillouin frequency shift depends on hydrogen concentration in the silica core with a rate of approximately 0.21 MHz/%H₂ . Influence parameters are discussed. We showed that temperature influence may be corrected with a collocated carbon-coated fiber.