Influence of spin-orbit coupling on the gamma-ray induced attenuation in high-OH silica fibers

CN Singh and XY Liu and BP Uberuaga and SJ Tobin, MATERIALS TODAY COMMUNICATIONS, 35, 106085 (2023).

DOI: 10.1016/j.mtcomm.2023.106085

There is an ever-increasing demand for radiation-tolerant optical systems in space and nuclear applications. This motivates leveraging advanced modeling techniques for the rational design of radiation-hard, application-specific optical materials. Here we used molecular dynamics, density functional theory, and solution of Maxwell's equations to understand the role of point-defects on the radiation-induced attenuation in wet fused silica (a-SiO2:OH). We apply this approach to study y-irradiated optical fibers, and find theoretical evidence that non-bridging oxygen-hole centers (NBOHC) are the primary microscopic defect responsible for radiation-induced attenuation in the visible- range. The nature of the defect states and implications for fiber efficiency are discussed. Spin-orbit coupling is found to play an important role in defining the optical properties of gamma-ray induced defects.

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