Generation of UV-defects in UV fibers: comparison between different pulsed UV lasers

Abstract

Temporal and spectral Laser-induced UV-loss studies in DUV-fibers with undoped synthetic silica core, mainly low-OH silica and modifications, were carried out with an automated set-up using pulsed 213 nm, 266 nm and 355 nm Nd-YAG Lasers. A multiple Gaussian band approximation was used to separate the individual but superimposed optically active UV defects leading to new temporal results of the individual UV defects. The curve shape of spectral losses was found to be different and strongly influenced by the Laser wavelengths, which are within absorption bands in low-OH silica, reducing the correlated defect at the beginning of irradiation significantly. In addition to solarization caused by 266 nm Laser damaging, annealing of some defects was observed. Depending on the fiber type, including hydrogen-treated types, different time constants were determined. Obvious transformations were observed during damaging with Lasers and/or broadband D2-lamp. Finally, an improved fitting of the UV attenuation or UV-induced losses in UV-fibers around 250 nm (ODC-II region) was possible by introducing two bands with slightly different peak wavelengths and temporal behaviors.