Functionalized Microstructured Optical Fiber for Magnetic-Field Sensing in Radiation Environments

A functionalized microstructured silica-based optical fiber, displaying significant magneto-optical effects in the
$C$
-band telecommunication wavelength (1530–1565 nm) has been developed by adding a sol-gel layer doped with magnetic nanoparticles around its pure silica core. The fiber was subjected to X-rays at room temperature up to a total ionizing dose (TID) of 500 kGy(SiO2)–50 Mrad–at a dose rate of 9.5 Gy(SiO2)/s. The magneto-optical responses of the functionalized fiber under a rotating permanent NeFeB magnet were investigated prior to, during, and after the irradiation using a dedicated setup. The results show that the magneto-optical properties of the sample remain unaffected by such radiation constraints, keeping the same promising performances as the not-irradiated sample. An additional passive measurement was conducted with an even greater TID of 2.5 MGy, at the same dose rate, giving identical results. This work demonstrates the radiation resistance of such a functionalization process in order to develop magneto-optically sensitive optical fibers able to be implemented in harsh environments such as the ones encountered in fusion-devoted facilities or nuclear power plants.