Abstract Body

Optical sensing has been gaining relevance for decades now due to its cost-effectiveness, versatility, electromagnetic noise immunity and many other features. However, there are still big challenges when deploying this type of sensors in harsh environments. Specifically, when subjected to high doses of radiation, the fibers suffer a darkening called radiation-induced attenuation (RIA) that precludes optical transmission through the fiber. Some work has been devoted to the study of this phenomenon in the last 20-30 years [1], but there is still a lot to discover. Furthermore, it is not enough with knowing the causes and physical mechanisms behind radiation-induced attenuation, we need to find ways to mitigate this problem. A possible solution seems to be optical annealing (or photobleaching), in which a secondary light beam is introduced in the fiber to anneal away the defects responsible for the excessive attenuation. This work further investigates this effect and its applicability in high-radiation environments such as fusion reactors. In order to do that we look into the effect that 1050 nm photobleaching light has on transmission at 1550 nm at room temperature and liquid nitrogen temperature with radiation-hardened, fluorine-doped fibers under X-ray radiation in the 160 keV to 320 keV range.

References

[1] Sylvain Girard et al. “Overview of radiation induced point defects in silica-based optical fibers”. In: Reviews in Physics 4 (Nov. 2019). issn: 24054283. doi: 10.1016/j.revip.2019.100032.

Acknowledgment

Matt Lynch for greatly assisting the electronical components of the setup