Photoinduced changes in the ultraviolet absorption bands of GeO2–SiO2glasses have a clear significance in photosensitive processes. In this letter, the dynamics of bleaching and growth of absorption bands in highly photosensitive germanosilicate thin films following exposure to 248 nm excimer laser radiation are discussed. Strong evidence is found in support of a single‐photon process for the bleaching of a band at 238 nm and growth of a band at 202.5 nm as a source of photosensitivity. Calculated changes in refractive index are eight times greater than those found in two‐photon‐induced grating experiments. This suggests avenues for enhancement of photosensitive effects through proper materials conditioning. ©1995 American Institute of Physics.