title: Optical thermometry based on the red upconversion fluorescence of Er3+in CaWO4:Yb3+/Er3+polycrystalline powder.
abstract: Based on the fluorescence intensity ratio method, the temperature-sensing behavior through thermally coupled levels (TCL) of the H11/22 and S3/24 states as well as the sub-levels of the F9/24 state of Er3+has been studied. The thermometry is observed to be dependent on the pump power for the H11/22 and S3/24 states, leading to an error of more than 20 K at 478 K. By utilizing the sub-levels of the F9/24 state, such a problem could be solved. The maximum sensitivity is about 0.15%  K-1at 298 K. This will provide guidance on selecting appropriate and practical TCL for precisely sensing the temperature.
authors.forename: Leipeng
authors.initials: L
authors.lastname: Li
authors.forename: Longjiang
authors.initials: L
authors.lastname: Zheng
authors.forename: Wei
authors.initials: W
authors.lastname: Xu
authors.forename: Zhang
authors.initials: Z
authors.lastname: Liang
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhou
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Zhang
authors.forename: Wenwu
authors.initials: W
authors.lastname: Cao