Irradiation of hydrogen loaded or flame brushed phosphorus doped,germanium free silicaglass with a 193‐nm ArF excimer laser changes the optical absorption at ultraviolet wavelengths by 40–140 dB/mm and the refractive index by more than 2×10−4. Bragg gratings with 90%–95% reflectivity are photoinduced in channel optical waveguides made from this glass. The thermal stability of the photosensitivity is measured by annealing up to 700 °C.