UV-irradiation-induced structural transformation of germanoscilicate glass fiber.

Raman spectra of germanosilicate core fibers before and after UV irradiation were investigated. Significant changes of the Raman spectra after irradiation indicate transformation of the glass structure. A possible interpretation of the observed changes is proposed.

Effects of drawing tension on the photosensitivity of Sn-Ge- and B-Ge-codoped core fibers.

The influence of drawing tension on the formation of Bragg gratings in B-Ge- and Sn-Ge-codoped core fibers is investigated by transmission and stress measurements. With increasing drawing tension, the axial stress is reduced in the B-Ge-codoped core but increased in the Sn-Ge-codoped core. A higher drawing tension leads to a photosensitivity enhancement and an increase of the core stress during the grating formation in B-Ge-codoped fibers.