γ and X ray irradiation effects on H2 unloaded and loaded P doped optical fiber
Résumé
P doped optical fibers are employed for the production of optical amplifiers and laser. In silica the P is mainly inserted in O=PO3 tetrahedra, in which the P forms a P=O linkage. P related radiation induced defects are responsible for optical absorptions (OA) that modify the fibers transmitting
features. Griscom identified two paramagnetic phosphorous oxygen hole centers (POHC) named stable and metastable. The first is considered the origin of OA band set 2.2, 2.5 and 5.3eV, while the other is considered responsible for an OA band at 3.1eV. In P doped fibers H2 loading was employed to produce fiber bragg grating, these materials feature lower radiation induced OA in the visible range and a reduction of the induced
POHC. In this work we studied irradiated P doped fibers by electron paramagnetic resonance, Raman and confocal luminescence microscopy
spectra to deepen the understanding of the radiation effects. The data indicate that stable and metastable POHC are induced under γ irradiation from 1 to 7.8MGy their concentrations appear independent from the dose. The Raman spectra indicate that the radiation does not modify the matrix
of the doped regions. Finally, under the X-ray irradiation we proved that the H2 loading decreases the amount of the induced POHC even if the irradiat
ion is performed several days after the loading, this result being relevant for their concrete application.