Temperature and polarization dependence of radiation-induced attenuation in pure-silica-core PANDA optical fiber

Abstract

Radiation-induced attenuation (RIA) spectra (700–1700 nm) in a pure-silica-core PANDA fiber were measured during and after γ-irradiation at room temperature (RT), −60 °C, and liquid nitrogen temperature (LNT) with the probe light polarization directed along each principal axis. The RIA difference between the polarizations was found to be largest at −60 °C, smaller at LNT and smallest at RT. At −60 °C, RIA for light codirected with the slow axis (RIAslow) proved to be greater than RIAfast throughout the spectrum, the RIA difference at λ = 1550 nm being 15% at the end of irradiation at a dose of 1 kGy (0.80 Gy/s) and increasing to 51% already in 10 min of post-irradiation recovery. RIAslow and RIAfast spectra measured at −60 °C were decomposed into RIA bands due to different types and classes of self-trapped holes (STHs) in the silica network. The origin of the RIA difference at λ = 1550 nm was thus explained in terms of the specific STH bands, of which the amplitudes turned out to be polarization dependent.