Pulsed-X-ray-irradiation of radiation-resistant PANDA fibers: Dependence on dose, probe light power, and temperature

Abstract Radiation induced attenuation (RIA) at wavelength λ = 1.55 μm was studied upon pulsed-X-ray irradiation in radiation-resistant fibers of the “PANDA” type of two chemical compositions having an undoped-silica core and an N-doped-silica core. The conditions were different among irradiations: dose, probe light power, and temperature. An explanation was proposed for the different time lag between the pulse and the inherent self-trapped holes (STHs) absorption maximum in fibers with different network strain. At low probe power and temperature, network strain required for the occurrence of strain-assisted STHs was found to be caused by stress-applying rods. Post-pulse RIA in the N-doped PANDA was assumed to be due to the 2.6-eV inherent STHs and 1.63-eV strain-assisted STHs. For the first time, RIA photobleaching was observed in the N-doped PANDA. The dependence of RIA on dose per pulse proved to obey a power law for both PANDA types. In various irradiation conditions, on an average, the N-doped PANDA tended to be superior at small post-pulse times, undoped PANDAs, at large post-pulse times.