Distributed Optical Fiber Sensor Allowing Temperature and Strain Discrimination in Radiation Environments

We evaluate the potential of a new architecture of distributed optical fiber sensor (DOFS) to discriminate between the temperature and strain changes along a single optical fiber exposed to radiation. This DOFS exploits the measurements of both the Landau-Placzek ratio (LPR) and the Brillouin frequency shift (BFS) to achieve the discrimination between the two parameters on up to 10 km of fiber with a spatial resolution of 1 m. We demonstrate that the LPR remains unaffected up to MGy(SiO2) dose levels, whereas the BFS is only slightly shifted by the radiation. The measured radiation-induced BFS is strongly reduced in radiation-hardened fluorine-doped single-mode optical fibers. Combining the DOFS architecture and the fiber allows discriminating temperature and strain using a single optical fiber up to megagray dose levels.