Multipath optical thermometry realized in CaSc <sub>2</sub> O <sub>4</sub> : Yb <sup>3+</sup> /Er <sup>3+</sup> with high sensitivity and superior resolution
Guotao Xiang, Qing Xia, Su Xu, Xiuchong Liu, Sha Jiang, Yongjie Wang, Xianju Zhou, Li Li, Li Ma, Xiaojun Wang, Jiahua Zhang
Abstract
Abstract Design and fabrication of contactless optical thermometer with rapid and accurate performance has become a research hotspot in recent years. Herein, CaSc 2 O 4 : Yb 3+ /Er 3+ is employed as the intermediary for temperature sensing under the excitation of 980 nm, which is proven to afford an ultra‐sensitive and high‐resolution optical thermometry in multiple ways based on the fluorescence intensity ratio ( FIR ) technology. The optimal thermal sensing behaviors are realized by the FIR of Er 3+ : 2 H 11/2 → 4 I 15/2 to 4 S 3/2 → 4 I 15/2 transition, which has a relative sensitivity of 1184/T 2 and a minimal resolution of 0.03 K along with a maximal absolute error of 0.96 K . Besides that, the FIR between the thermally coupled Stark sublevels of Er 3+ : 4 F 9/2 manifold ( FIR R ) as well as that of Er 3+ : 4 I 13/2 manifold ( FIR N ) can also provide excellent optical thermometry. The relative sensitivity of FIR R ‐based and FIR N ‐based optical thermometers are calculated to be 402/T 2 and 366/T 2 , respectively, with a same minimal resolution of 0.09 K , which possess the potential to be used for biomedicine due to the inherent advantage of their operating wavelengths located in the biological window. The results demonstrate that CaSc 2 O 4 : Yb 3+ /Er 3+ is a promising candidate for temperature sensing with multipath, high sensitivity, and superior resolution.