A Low Pumping Power Excited Er³⁺/Yb³⁺ Co-Doped Tellurite Temperature Sensor for Thermal Monitoring of MOSFET in Complex Circuits

Er3+/Yb3+ co-doped tellurite glass (TeO2-ZnO-WO3-Li <tex-math notation="LaTeX">_2O </tex-math> -BaF2-Nb2O3-Er2O3 + Yb2O3, TZWLBN) was investigated in the range of 253–443 K, and by varying the molar ratio of Yb3+ ions, the ion concentration of the strongest luminescent emission was found. Based on it, by combining mold casting and fiber drawing techniques, a no-core tellurite fiber (NTF) was fabricated, and then connected with two multimode fibers (MMFs) to form a temperature sensor. Under a pumping power of 2.20 mW, a comprehensive evaluation was conducted to investigate the temperature sensing characteristics of this sensor, employing the fluorescence intensity ratio (FIR) technique. The repeatability and stability of the experimental protocol were established through numerous heating-cooling cycles and constant temperature test. The highest possible absolute and relative sensitivities were determined as 0.00264 and 0.0114 <tex-math notation="LaTeX">K^-1 </tex-math> . The temperature sensor exhibited a maximum temperature error of 0.88 K when employed for monitoring the temperature of the metal–oxide–semiconductor field effect transistor (MOSFET) in complex circuits, thereby demonstrating its practical applicability in thermal detection scenarios.