Radiation-Induced Attenuation Data of Polarization-Maintaining Fibres

Radiation-induced attenuation measurements have been carried out on four different commercial optical fibres, three of them being polarization-maintaining. Irradiations have employed a
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Co gamma-ray source and in order to perform these in situ measurements, two optical setups have been developed. First, the DFB bench operates at 1542 nm with a laser chip injecting in the DUT a few tens of mW. Second, the halogen bench works with a white light source whose spectrum is filtered from 400 to 1550 nm. Optical power injected into the DUT is less than 10 nW in a spectral band 2-3 nm wide. Comparing measurements of both benches around 1540 nm allows to reveal photobleaching effect within some commercial optical fibres. A strong radiation-induced absorption band centered around 1250 nm has been observed during the irradiation of one fibre. To our knowledge, it cannot be tied, at this time, to any clearly identified color center.