Pump induced refractive index changes in gamma-irradiated Yb-doped optical fibers

Rare-earth-doped optical fibers are considered as possible candidates for air and space applications such as optical sensors and optical inter-satellite telecommunication links. The use of Yb-doped optical fibers on the satellite board emerges the challenge of their radiation resistance. The dose of ionizing radiation that such fiber absorbs during 15 years in open space is estimated to be up to 2 kGy (for SiO₂ based fiber). The radiation exposures lead to the excitation of electrons and the subsequent formation of the color centers in activated glasses affecting the performance of active devices. Monitoring of the population inversion in Yb-doped optical fibers through the refractive index changes effect proposed here allows to evaluate the degree of fiber degradation under γ-radiation.