Radiation hardening of optical fibre links by photobleaching with light of shorter wavelength

The influence of additionally injected short-wavelength photobleaching light on the radiation hardness of Ge-doped graded index fibres working at 1300 nm wavelength is investigated. Predictions are complicated by the fact that more efficient shortwave bleaching light experiences higher radiation-induced loss. Promising results are found for low fibre temperatures (< -50 deg C) and bleaching light of about 835 nm wavelength.