Brillouin sensing in optically heated Co2+-doped fibers

In this paper, we demonstrate the use of single-mode Cobalt-doped fibers for active distributed temperature sensing with optical heating. A high-power EDFA at 1550nm is used for optically heating the fiber, while a Brillouin Optical Frequency-Domain Analysis (BOFDA) set-up operating at 850nm is employed to monitor the corresponding temperature changes. Owing to the use of a dual wavelength scheme, longer sensing distances can be reached even with relatively high doping concentrations. As a proof of concept, we demonstrate the possibility to distinguish two 1-m fiber sections, one immersed into water and another one surrounded by air.