Defect production in silica fibers doped with Tm^3+

Irradiation of Tm3+ fibers with blue light at 476 nm induces a broad-bandwidth loss in these fibers. We have measured the spectral dependence of the loss for both silica–germania and silica–alumina fibers and show through micro-Raman studies of the core regions of the fibers that this induced loss is correlated with the production of structural defects in the glass host.