Ag–CdS-Coated Cladding-Modified Fiber-Optic Sensor for Detection of NO2 Gas

Abstract

In this study, a cladding-modified fiber-optic sensor is reported for NO2 gas detection. Monitoring the purity of air is the need of the hour, with the growing technologies. Hence, in this work, Ag-doped CdS is coated over the cladding-removed region of 3[Formula: see text]cm length by Chemical Bath Deposition (CBD) which acts as the gas-sensing medium. Ag–CdS is coated over four fibers each with a different coating duration of 10[Formula: see text]min, 20[Formula: see text]min, 30[Formula: see text]min and 40[Formula: see text]min. Characterization of Ag–CdS is done by Scanning Electron Microscope (SEM), UV-visible absorption spectroscopy and UV-visible reflectance spectroscopy. The spectral response for different concentrations of NO2 is studied on the four fibers separately, and it is analyzed and compared. The minimum detection limit is 100[Formula: see text]ppm and the response time is 10[Formula: see text]min. Out of the four fibers, Ag–CdS-30 exhibited the best response with a sensitivity of 15.5%. The results are compared with cladding-modified fiber coated with CdS, which was reported previously. The effect of Ag-doping is analyzed.