Yb3+/Er3+-codoped GeO2-PbO-PbF2 glass ceramics for ratiometric upconversion temperature sensing based on thermally and non-thermally coupled levels

The contactless real-time temperature sensing technique with high temporal and spatial resolution is in high demand for the countless applications. Here, the Yb³⁺/Er^3+-codoped GeO₂-PbO-PbF₂ glass ceramics synthesized via the melt-quenching technique has been presented as an optical thermometer. The thermal sensing was designed based on the temperature dependent fluorescence intensity ratios of thermally (²H_11/2 and ⁴S_3/2) and non-thermally (²H_11/2 and ⁴F_9/2) coupled Er³⁺ levels. The ratiometric techniques provide the thermal sensing within the temperature range of 300-466 K. The absolute and relative thermal sensitivities as well as the temperature resolution were calculated and compared with other Yb³⁺/Er³⁺-doped materials. The temperature of the microelectronic component on the printed circuit board was defined using the optical thermometry as a proof of concept revealing Yb³⁺/Er^3+-codoped GeO₂-PbO-PbF₂ phosphor to be a promising candidate for precise non-contact thermal sensor.