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

Abstract

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.