Defect centers in a germanium-doped silica-core optical fiber

The radiation-induced defect centers in a low-loss Corning germanium-doped optical fiber have been studied. In addition to silicon E′ centers, four germanium-related centers, corresponding to electrons trapped at the site of oxygen vacancies in s p3 orbitals of germanium ions with zero to three next-nearest-neighbor germaniums, were observed. A model which assumes Gaussian distributions in the excited-state energy-level splittings has been successfully used to computer simulate the ESR spectrum of the irradiated fiber.