Attenuation Nature of Optical Fibers with Oxygen-Deficit Silica Core after γ-Irradiation with 1 MGy Dose

The present work aims to investigate the nature of γ-irradiation induced attenuation in the near-infrared spectral region for single-mode optical fibers with a core made of oxygen-deficit silica glass and a fluorine-doped cladding. The optical fibers were fabricated by the MCVD method. After the irradiation with a dose of 1 MGy the optical fiber attenuation in the spectral range 1200–1600 nm was measured after 2 h, 3 and 10 months. The radiation induced attenuation in the 1600 nm region is higher and more stable than at 1300 nm. The silica glass phonon spectrum change is indicated by the measurements of the spectral dependence of absorption in the region of 1400–700 cm⁻¹ when silica glass grains are irradiated with a dose of 1 MGy. The increased oxygen content in the glass enhances the destruction of its network. The nature of radiation-induced attenuation of fibers in the 1900 nm spectral region is justified by the change in the intensity of the silica glass fundamental band fourth overtone. The attenuation at γ-irradiation with an increasing wavelength in such single-mode fibers is also related to the penetration of optical radiation into the cladding, the radiation resistance of which is less than that of the core material.