In-Situ X-Ray Monitoring Using Specialty Optical Fibers and Determination of Their Synchrotron X-Ray Computed Tomography Imaging Conditions

Specialty fibers are designed as a diverse and innovative class of optical waveguides that meet specific performance criteria beyond those of standard telecom fibers. These designs are engineered with advanced materials possessing unique structures, compositions, or geometry for various industrial applications such as sensing. For instance, rare Earth (RE) elements such as Yb, Er, Nd, and Tm have been incorporated into the core of optical fibers for high-power fiber laser applications due to their strong absorption and emission bands. Yb-doped optical fibers exhibit high quantum efficiency, which facilitates the production of high-power fiber lasers with optical-optical efficiencies reaching around 90%. However, radiation-induced defects occur due to irradiation, leading to a degradation of beam quality. Yb-doped fibers are susceptible to degradation from radiation sources such as high-energy particles and gamma rays [2], which results in a loss of performance in optical transmission and light amplification. This type of degradation is referred to as radiation-induced attenuation (RIA), as the formation of color centers directly affects the transmission properties of optical fibers, consequently leading to a decline in their performance.