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Abstract: Several single mode silica-based fibers with different levels of erbium concentrations have been tested under 60Co gamma radiation. Irradiation has been performed at a dose-rate of ∼30Gy/h to a total dose of ∼2kGy. Transmission spectra were measured in situ in a spectral range from 1250 to 1630nm. The measurements show no detectable change in the Er-ions luminescence and absorption spectrum profiles, while a significant (∼dB/m/kGy at 1530nm) increase in transmission losses is attributed to the silica host matrix modifications. This conclusion is drawn based on the post-irradiation photo-luminescence analyzes realized with a confocal micro-spectrometer (514.5nm excitation, P ∼2mW). [Copyright &y& Elsevier]

Abstract: We studied the efficiency of a hydrogen-treatment in different pure silica core fibres irradiated by γ-ray in an attempt to decrease the radiation-induced absorption (RIA). It is observed that the effect of hydrogen already reduces the drawing-induced band commonly observed in low-OH fibres. During irradiation we observe a large increase of the radiation-induced OH growth with a corresponding significant reduction of the radiation-induced absorption at 0.63μm. The presence of hydrogen also reduces the transient radiation-induced absorption at 0.7μm sometimes observed in low-OH/low-chlorine fibres and believed to pertain to self-trapped holes (STHs). [Copyright &y& Elsevier]

Abstract: We propose a kinetic approach to the decomposition of the radiation-induced absorption spectra into individual Gaussian absorption bands. It is based on the correlated analysis of a series of induced absorption spectra obtained in the course of multi-step irradiation and during room temperature long-term post-radiation annealing. The methodology is demonstrated using data on Co60 gamma irradiated samples of commercial boro-silicate glass N-BK7 from SCHOTT. We show that physically meaningful spectroscopic parameters of absorption bands can be obtained without a priori knowledge of the band peak position and bandwidth. [Copyright &y& Elsevier]

Abstract: We investigated pulsed-X-ray-induced attenuation in two pure-silica-core (PSC) optical fibers with low-chloride (Cl) and different hydroxyl (OH) contents. We measured at room temperature the temporal (100ms–1000s) and spectral (0.73–3.1eV) variation of the induced optical absorption after a 1MeV X-ray pulse in both low- and high-OH PSC multi-mode fiber samples. A component of the transient loss in the low-OH sample was found to comprise absorption bands at 1.63 and 1.88eV (760 and 660nm) arising from self-trapped holes (STHs). Already known to be unstable at room temperature, STHs appear to play a key role in the transient responses of low-OH/low-Cl pure-silica-core fibers in the visible/near-infrared part of the spectrum. [Copyright &y& Elsevier]