SPECTROSCOPY OF DEFECTS IN GERMANIUM-DOPED SILICA GLASS

We present data concerning the dynamics of photoexcitation of defect c enters in germanium-doped silica glass optical-fibers and fiber prefor ms. It is shown that two-photon absorption of mode-locked.and Q-switch ed light at 527 nm results in partial ionization of the germanium oxyg en deficiency center (GODC) 400-nm luminescence band. This bleaching i nduces loss in the 320-600-nm wavelength range, which we argue is due to the introduction of Ge(1) centers and charges trapped at structural defects in the glass. The excitation and relaxation of dynamics of th e GODC are analyzed by examining the photoluminescence and absorption spectra, and two models are proposed to explain the observed behavior.