Based on luminescence intensity ratio (LIR) technology, the noncontact upconversion (UC) optical temperature sensor has aroused a great deal of interest due to its great application prospects in some extreme environments. However, most of the studies focused on improving its sensitivity due to the fact that the sensitivity can be influenced by many external field factors, such as the power density and pulse width of pumping sources or temperature. Herein, a green-emitting UC phosphor Sr₂InF_7: Yb³⁺, Er³⁺ was developed as a potential thermometer, which retained bright green emission under 980 nm excitation with different pulse widths and power densities or at different temperatures; the possible mechanisms are discussed in detail. Its sensitivity almost remained constant when using both continuous wave (c.w.) and pulsed laser or different power densities, which meant the sensitivity of Sr₂InF_7: Yb³⁺, Er³⁺ was independent of the characteristics of pumping laser. A flexible thin-film thermometer composed of Sr₂InF₇: 2%Yb³⁺, 2%Er³⁺ was also fabricated to detect the temperature of microelectronic components, which can not only accurately measure the temperature of the working electronic circuit board but also exhibit excellent repeatability. The results indicated that the present noncontact UC temperature sensor showed stable green emission and thermometric sensitivity as well as the possibility of replacing the traditional thermometers.

中文翻译：

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上转换荧光粉 Sr2InF7：Yb3+、Er3+ 的与外场无关的测温灵敏度和绿光发射

基于发光强度比（LIR）技术的非接触式上转换（UC）光学温度传感器由于其在一些极端环境中的巨大应用前景而引起了人们的极大兴趣。然而，由于灵敏度会受到许多外场因素的影响，例如泵浦源的功率密度和脉冲宽度或温度，因此大多数研究都集中在提高其灵敏度上。在此，绿色发射UC磷光体Sr ₂ InF _{7 ：} Yb ³⁺，Er ³⁺被开发为潜在的温度计，在 980 nm 激发下具有不同的脉冲宽度和功率密度或在不同的温度下保持明亮的绿色发射；详细讨论了可能的机制。在使用连续波（cw）和脉冲激光或不同功率密度时，其灵敏度几乎保持不变，这意味着Sr ₂ InF _{7 ：} Yb ³⁺，Er ³⁺的灵敏度与泵浦激光的特性无关。_{由 Sr 2} InF ₇ : 2%Yb ³⁺ , 2%Er ³⁺组成的柔性薄膜温度计还被制造用于检测微电子元件的温度，它不仅可以准确地测量工作电子电路板的温度，而且具有出色的重复性。结果表明，目前的非接触式 UC 温度传感器显示出稳定的绿光发射和温度测量灵敏度，以及取代传统温度计的可能性。