Lossy Mode Resonance-Based Fiber Optic Sensor for the Detection of As (III) Using $\alpha$ -Fe 2 O 3 /SnO 2 Core–Shell Nanostructures

Fabrication and characterization of a fiber optic sensor employing lossy mode resonance (LMR) have been carried out for the detection of As (III) using core–shell nanostructures as a sensing layer. Two kinds of sensor probes are designed as one, utilizing the layer of tin oxide (SnO 2 ) nanoparticles (NPs) and the other having coating of SnO 2 thin film over unclad core of the fiber. Both the probes are further coated with $\alpha$ -Fe 2 O 3 /SnO 2 core–shell nanostructures. To check the response of both the probes, the absorbance spectra of the transmitted light at the output end of the probe are recorded for different concentrations of As (III) samples around the probe. The peak absorbance wavelengths are extracted from the absorbance spectra for different concentrations of As (III) to calibrate both the sensor probes. The results show maximum sensitivity toward As (III) for the probe coated with SnO 2 NPs as LMR supporting layer. The sensor has numerous advantages like selectivity, easy handling, simple design, fast response, online monitoring, and capability of remote sensing.