Effect of radiation on the bandwidth of graded index fibres

The influence of gamma radiation on the bandwidth of graded index fibres of four different manufacturers is measured at about 840 and 1300 nm wavelength. Increase as well as decrease is observed, depending on fibre type and wavelength. Differential mode attenuation and mode delay measurements, as well as examination of light emission distribution at the fibre endface before and after irradiation are performed to explain the results.