An optical fiber apparatus is suitable to operate under irradiation, more particularly to mitigating the damage of a rare-earth-doped optical fiber element as part of an optical fiber assembly causes by irradiation. The irradiation mitigation attributes to a photo-annealing apparatus including at least a shorter wavelength photo-annealing spectral content, which is relative to that of a pump light source, for effectively photo-annealing the rare-earth-doped fiber element. Photo-annealing by such shorter wavelength light results in a fast and nearly complete recovery of radiation induced attenuation of the rare-earth-doped optical fiber element in the wavelength range from 900 nm to 1700 nm.