Defect formation and recovery processes in hydrogen-loaded silica fibers

Defect formation in hydrogen-loaded silica fibers for deep ultraviolet (DUV) light applications was investigated. Absorption spectra in the range including vacuum UV (VUV) light were measured, and an absorption band at 6.7 eV has been found to be a dominant origin of lowering transparency for ArF excimer laser. This band seems to be strongly correlated to the E′ center. On the other hand, the nonbridging oxygen hole center, giving absorption bands at 4.8 and 2.0 eV, could not be observed in the fiber used here. Furthermore, recovery after the laser irradiation and successive degradation by additional irradiation of laser or D2 lamp were analyzed.