Non-linear optical properties of silica-glass-core-fiber waveguides under intense pulsed reactor irradiation

The light emission and transient optical loss (TOL) of KU-1 (Russia) and K-3 (Japan) fibers during pulsed reactor irradiation (pulse duration 80 μs, dose rate < 7 × 1016 n/cm2 s) have been measured in the visible region. The intensity of fast component of light emission obeys sub-linear dose rate dependence. The intensity of light emission and the TOL depend on the intensity of probing light. Lower intensity of the light emission is observed for higher intensity of probing light. The light emission quenching occurs for wavelengths shorter or longer than the wavelength of probing light. Probing with light enhances the TOL and shortens the decay time of TOL. A `two-photon-flowsʹ model has been introduced to analyze correlation between the effect of light emission quenching and the TOL enhanced by probing light. The effect of light emission quenching provides means to control the optical properties of fibers in radiation environments.