Influence of hydrogen on the colour center formation in optical fibers induced by pulsed UV-laser radiation. Part 1: All silica fibers with high-OH undoped core

Creation of colour centers in fused silica fibers is the main problem during transmission of high-power UV-laser radiation, that leads to solarization and hence decreasing transmission. By loading commercial fused silica fibers with hydrogen, we found a way to improve the transmission properties through the reduction or suppression of solarization. The transmission behaviour of hydrogen loaded high-OH fibers for 266 nm pulsed laser radiation has been studied. Spectroscopic experiments explain many aspects of colour center creation and annealing and allow the determination of kinetic data for the underlying reactions. Based on this work it is possible to realize fiber optic beam delivery systems for frequency quadrupled Nd:YAG lasers and for other high power UV laser sources like excimer-lasers. These results may also be useful for the improvement of bulk fused silica for UV applications.