PCF based modal interferometer for lead ion detection

A compact, reliable, and fast responsive PCF (photonic crystal fiber) based modal interferometric sensor for lead ion detection is proposed and experimentally demonstrated. The sensor has been fabricated by splicing a small section of PCF with SMF (single mode fiber) followed by collapsing the air holes of PCF at its tip. The interferometer is dip coated with chitosan-PVA (polyvinyl alcohol) and glutathione functionalized gold nanoparticles. Three probes have been fabricated, and the maximum sensitivity has been found to be 0.031 nm/ppb for lead ions whereas the detection range has been considered from 0 ppb to 50 ppb. The probe has been found to have a faster response time of similar to 10 s. Furthermore, the sensor has been found to be less responsive towards other heavy metal ions, thereby demonstrating its selectivity towards lead ions. Besides, a section of FBG (fiber Bragg grating) has been embedded into the interferometer and the temperature response of FBG peak along with interference spectra has been investigated for better accuracy. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement