Kinetics of UV-induced blue luminescence linked with the observation of the local mean index in fiber Bragg gratings.
We exposed H2-loaded optical fibers to cw UV light and simultaneously measured the intensity of the blue luminescence from the fiber core. The UV-induced blue luminescence experiences a non monotonous evolution and thus cannot be correlated to the refractive index changes. However, a quasi-linear relationship has been found between the increase of the blue luminescence and the refractive index changes in the range 5 10-4 < Deltan mean (or Deltan mod) < 2.5 10-3. Using this property, we analyze a fiber Bragg grating by focusing a UV beam probe onto the fiber core and we record the UV-induced blue luminescence at the end of the fiber. By scanning the UV beam along the fiber, we measure thus the axial profile of the refractive index changes with a spatial resolution of 1 mum.
Paccou
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Lancry
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Douay
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