Gamma-Ray Radiation Effect on Non-Resonant Third-Order Optical Nonlinearity of Germano-Silicate Optical Fiber

Gamma-ray radiation effect on the non-resonant third-order optical nonlinearity of the germano-silicate optical fiber has been investigated by the continuous-wave self-phase modulation method. The nonlinear refractive index, n
₂
, of the gamma-ray irradiated optical fiber was found to increase linearly with the increase of the gamma-ray induced absorption. The increased n
₂
has been mainly ascribed to the NBOs and Ge-realted radiation-induced defects having hyperpolarizabilities.