Vol. 55, Issue 1, pp. 63-76 (2025)

Abstract

A dual parameter fiber optic sensor is proposed, which is based on a cascade single mode fiber (SMF)-capillary-no core fiber (NCF)-SMF (SCNS) structure. The sensor introduces a capillary to the conventional SMF-NCF-SMF (SNS) structure, which improves the excitation co-efficient of the higher order modes in the NCF. The optimized ZnO film thickness of the SCNS sensor is 100 nm by simulation, which can enhance the sensitivity of the sensor greatly. The experimental results show that the resonant wavelength has different sensitivities to NH₃ concentration and temperature. The maximum NH₃ concentration sensitivity is 35.52 pm/ppm, with a detection limit of 2.309 ppm, and the maximum temperature sensitivity is 25.85 pm/°C. Based on the different spectral responses, a cross-matrix is developed to enable the simultaneous measurement of temperature and NH₃ concentration.