Simultaneous Distributed Sensing on Multiple MgO-Doped High Scattering Fibers by Means of Scattering-Level Multiplexing

We introduce a novel multiplexing technique applied to optical fiber distributed sensors, based on optical backscatter reflectometry (OBR) and high-scattering MgO-doped fibers. In this paper, we demonstrate the possibility of simultaneously detecting multiple fiber with a single scan using an OBR distributed sensor, and successfully discriminating each sensing region (with ~1 mm spatial resolution). The sensing element is a high-scattering fiber with MgO-based nanoparticles doping in the core, that emits a scattering signal more than 40 dB larger than a standard fiber, while having similar temperature and strain sensitivity. Multiplexing occurs as the scattered light from a sensing fiber overshadows the amount of scattering occurring in all the other channels. The setup has been validated for temperature sensing and implemented in an epidural catheter with multiple fibers fixed to the outer walls for strain sensing. The proposed solution goes beyond the multiplexing methods which exploit 1 × N switches, as the multiplexing is simultaneous and not rearranged in different time slots.