Refractive Index Sensor by Interrogation of Etched MgO Nanoparticle-Doped Optical Fiber Signature

Traditional fiber-optic refractive index (RI) sensors require a reflective or resonant device in fiber (such as a grating, an interferometer, a taper, or a plasmonic device) and a spectral domain detection. In this letter, we demonstrate and experimentally validate, the possibility to fabricate a minimalistic RI sensor, based on the wet-etching of an enhanced backscattering fiber made with a core doped with MgO-based-nanoparticles. Interrogation is performed in the length domain, by detecting and correlating the random losses of the fiber with an optical backscatter reflectometer. The sensitivity is 5.25 mm/RIU with 9.6 μm resolution, corresponding to 9.69 ps/RIU.