Measurement of the birefringence variation induced by dihydrogen diffusion into a polarization-maintaining fiber

We report continuous measurements of the transmission spectrum of a fiber loop mirror interferometer composed of a Panda-type polarization-maintaining (PM) optical fiber during the diffusion of dihydrogen (H2) gas into the fiber. Birefringence variation is measured through the wavelength shift of the interferometer spectrum when the PM fiber is inserted into a gas chamber with H2 concentration from 1.5 to 3.5 vol.% at 75 bar and 70 degrees C. The measurements corre-lated with simulation results of H2 diffusion into the fiber lead to a birefringence variation of -4.25 x 10-8 per mol m-3 of H2 concentration in the fiber, with a birefringence vari-ation as low as -9.9x10-8 induced by 0.031 mu mol m-1 of H2 dissolved in the single-mode silica fiber (for 1.5 vol.%). These results highlight a modification of the strain distribution in the PM fiber, induced by H2 diffusion, leading to a variation of the birefringence that could deteriorate the performances of fiber devices or improve H2 gas sensors.(c) 2023 Optica Publishing Group

Automated summary

Continuous measurements of the transmission spectrum of a fiber loop mirror interferometer composed of a Panda-type polarization-maintaining (PM) optical fiber during the diffusion of dihydrogen (H2) gas into the fiber are reported. The birefringence variation caused by H2 diffusion in the fiber is measured and correlated with simulation results, highlighting the strain distribution modification and its potential impact on the performance of fiber devices and H2 gas sensors.