The effect of optical signal intensity at the wavelength of system operation (0.85 μm) on the recovery of the radiation-induced attenuation in optical fiber waveguides following exposure to a 3700-rad dose of ionizing radiation has been investigated. Photobleaching has been observed in both pure and doped silica core fibers, although the effect is more pronounced in the former.
E. J. Friebele and M. E. Gingerich, "Photobleaching effects in optical fiber waveguides," Appl. Opt. 20, 3448-3452 (1981)