DYNAMIC AND ORIENTATIONAL BEHAVIOR OF UV-INDUCED LUMINESCENCE BLEACHING IN GE-DOPED SILICA OPTICAL-FIBER

We report two experiments on UV light-induced bleaching of the 400-nm luminescence associated with the 240-nm absorption band in Ge-doped optical fiber. We have measured the dynamics of the bleaching for different UV intensities and show that it is well fitted by a stretched exponential function, which indicates a site-dependent bleaching rate. We have also shown that the bleaching is anisotropic, confirming a model in which the defects having a dipole moment aligned with the UV light polarization are preferentially excited and bleached.