UV-Radiation Induced Color Centers in Optical Fibers

Abstract

ABSTRACTParamagnetic color centers have been observed in germanium silicate and germanium phosphosilicate multimode optical fiber exposed to broadband ultraviolet light (2–5 eV). These centers are characterized by an ESR and optical absorption similar to 1 meV and 100 keV radiation induced defects and show an apparent saturation as the UV dose approaches 100 J/cm2. The UV induced ESR spectra are not identical to that induced by 60Co radiation however, similar Ge(2) and Ge(3) germanium defect signatures are apparent. For both compositions these centers are characterized by a rapidly increasing loss from 1.0 to 0.5 µm with an additional broad absorption peak at 1.5 µm for the phosphorus containing cores. We suggest that the UV induced optical absorptions for both compositions in the short wavelength range are due in part to the Ge(2) germanium substitutional sites and expect that the 1.5 µm absorption is due to the P1 phosphorus oxygen vacancy.