Gamma-Ray Dose-Rate Dependence on Radiation Resistance of Specialty Optical Fiber with Inner Cladding Layers

Abstract

A germano-silicate glass optical fiber with inner cladding layers of pure silica buffer and boron-doped silica was fabricated to enhance photosensitivity of fiber Bragg grating (FBG) maintaining the radiation resistance for sensing applications. The gamma-ray dose-rate dependence on the radiation-induced attenuation (RIA) and the peak shift of the FBG inscribed in the core of the fiber was investigated. As the γ-ray irradiation on the fiber with the FBG increased to 22.86 kGy/h, the reflected peak power increased together with small temperature increase but the transmitted power at 1550 nm decreased. While the Bragg reflection wavelengths were shifted toward longer wavelengths during the γ-ray irradiation, the FWHM bandwidth remained unchanged. The Bragg peak shift of the FBG was found to saturate at a 78 pm level and the RIA of 1.345 dB/m at 1550 nm was obtained with the accumulated dose-rate of 22.86 kGy/h.