Effect of nonradiative transitions on the EDF-based fiber-optic temperature sensor

In this paper, the response mechanisms of erbium-doped fiber (EDF)-based fiber-optic temperature sensors and the influence of nonradiative transitions on sensor sensitivity are experimentally investigated for the first time, and a sensitivity enhancement technology based on the lifetime differentiation of dual EDF is also proposed. First, the fluorescence temperature sensing mechanism and the influence of nonradiative transitions on the response characteristics of EDF-based fiber-optic temperature sensors are analyzed theoretically. Subsequently, experiments were conducted to further explore the properties of the fluorescence lifetime of EDF in response to temperature under the influence of nonradiative transitions by varying the length of the EDF to adjust the proportion of nonradiative transition. The experimental results demonstrate that the fluorescence lifetime of EDF exhibits non-monotonic changes under the influence of nonradiative transitions, and the sensitivity of the EDF-based fiber-optic temperature sensor also changes greatly from -0.00070 to 0.00054<i>m</i><i>s</i>/^∘<i>C</i> as the EDF length varies from 20 to 500 cm. Based on the influence mechanisms of nonradiative transitions on EDF-based fiber-optic temperature sensors, a sensitivity enhancement method is proposed by differentiating the fluorescence lifetimes of two segments of erbium-doped fibers with different lengths and opposite sensitivities, by which a measurement error of 2°C and sensitivity of -0.00135<i>m</i><i>s</i>/^∘<i>C</i> can be finally achieved within the temperature range from 37 to 223°C. This study provides insights into the influence mechanisms of nonradiative transitions on the fluorescence lifetime of EDF and contributes to the performance improvement of EDF-based fiber-optic temperature sensors.