Er/Yb/Ho tri-doped no-core fiber temperature sensor based on fluorescence intensity ratio technology: towards high stability and accurate measurements.

In this paper, the green upconversion (UC) fluorescence emission from / / tri-doped tellurite glass is investigated for temperature sensing. The doping of ions not only enhances the chance of energy level transition but also avoids the influence of the thermal effect caused by the proximity of and energy levels. The luminescence characteristics at different and ion concentration doping molar ratios were investigated, and the strongest luminescence characteristics were exhibited when the ion concentration was at 5 mol% and at 0.2 mol%. Based on this, a tri-doped - - (TZB) no-core fiber was fabricated and connected with multimode fibers (MMFs) to form a temperature sensor. The temperature sensing performance of the tri-doped TZB temperature sensor was evaluated in detail over the temperature range of 255-365 K. The repeatability and stability of the temperature sensor was experimentally verified. The / / tri-doped sensor can be used for noninvasive optical temperature sensing in the fields of environmental monitoring, biological sensing, and industrial process temperature control, etc.