Ag‐doped TiO2 (rAg/Ti, r 1−3 = 2, 4, 6 wt%) is synthesized by a hydrothermal technique. Different characterizations, that is, X‐ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) analysis, photoluminescence (PL) spectra analysis, X‐ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FESEM), energy dispersive X‐ray analysis (EDX), and Brunauer–Emmett–Teller (BET) analysis, are conducted to study the utility of the developed thin‐film material as a sensing medium over the fiber substrate. The as‐prepared material is hydrothermally deposited over the optical fiber to construct a fiber optic sensing probe. The optical properties of TiO2 are simulated theoretically by MATLAB simulation that reveals that optical absorption appears at the wavelength of 763 nm. The initial performance of the rAg/Ti‐based optical fiber is investigated with the amine group in the range of 500−1500 ppm and a satisfactory response is found toward ethylenediamine (EDA) analytes with average sensitivity (S av, in %) as 41.81 at 1200 ppm.

Synthesis of pure ZnO and bismuth-doped ZnO (xBi/Zn) (x ¼ 6 wt%) thin-film based optical fiber sensor and their material/optical characterization such as Brunauer-Emmett-Teller (BET) analysis, field-emission scanning electron microscopy (FESEM), and energy dispersive X-ray (EDX) analysis is reported. As-prepared material such as xBi/Zn is deposited over the optical fiber, and optimum clad thickness in the range of 2-5 μm is achieved through MATLAB simulation to enhance the feasible evanescent field interaction with gas analyte molecules. The modal field analysis of the sensing probe before and after the deposition of xBi/Zn is also studied using COMSOL Multiphysics Modeling software and find strong light propagation into the LP 04 mode. The sensing probes are tested in different chemicals and ethylenediamine (EDA) is found to be the most suitable candidate in the concentration range of 100-800 ppm. The response time of the ZnO and xBi/Zn-doped thin-film-based optical sensor is found to be 20 and 15 s, whereas the corresponding sensitivity (%) is 1.078 and 3.483, respectively. The repeatability test of the sensor is also carried out which reveals good response stability.