Distributed sensing based on Optical Backscattering Reflectometry (OBR) is a promising solution for medicalapplications, such as thermal ablation. OBR working principle is based on the change in pattern of small reflectionsfrom non-homogeneities inside the fiber as a response to applied strain and temperature. The advantageof OBR is its high resolution and sensitivity. However, since the scattering level is the same for standard singlemodefibers, OBR is unable to discriminate the pattern of different fibers when they are connected in parallel toa single channel. As a result, OBR detection is limited to a single sensing fiber and does not allow multiplexing.This work proposed a method to overcome the aforementioned limitation by the use of high-scattering fibers.Such fibers are achieved by doping their core with magnesium oxide particles, which size varies from 20 to 100nm. The backscattering level of nanoparticles doped fiber (NPDF) is 50 dB higher than of the standard fibers.Four NPDFs have been spliced to the standard single-mode pigtails with different length to achieve four sensingregions located at different distances from pigtails. The NPDF sensors have been connected to the OBR equipmentby the use of optical couplers and the backscattered pattern has shown four high-scattered sensing regionsseparated by low-scattering regions from standard fibers. The proposed setup has been applied in the thermalablation experiments and the 2-dimensional map of temperature change with time has been obtained.
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