ZnO nanostructures coated no-core fiber refractive index sensor

The combination of optical fibers with nanostructured films deposition offers potential opportunities and perspectives for the realization of novel optical sensors. A refractive index (RI) sensor based on ZnO as outer layer coating over no-core fiber (NCF) sensing region is proposed and experimentally demonstrated here. Different morphologies of ZnO nanoparticles have been achieved via hydrothermal method by controlling the growth time, temperature, and concentration of reacting solution. The proposed sensor detects power variation of transmitted light propagating through the fiber caused by a change in RI of the surrounding medium. Few basic material characterizations like FESEM, UV–Vis, PL spectroscopy, and XRD's were done to confirm the formation of ZnO nanolayer. The superior sensing performance are obtained for vertically oriented ZnO nanorods among the various nanostructures. It may be attributed due to the large and uniform surface area, better crystallinity, higher average dispersion relation, and excellent adhesion of analyte molecules. The most heightened average sensitivity of 799.42%/RIU with stable results is found for a wide RI range of 1.33–1.40 which could be applied in multipurpose chemical, physical, and biomedical sensing applications.