Achieving Efficient Optical Thermometry in Terbium-Doped Highly Transparent Ceramics

Temperature-responsive dynamics of excited-state population in terbium (Tb) ions may open the door for the advancement of high-performance photothermal feedback windows. However, obtaining robust luminescence and superior transparency in Tb-doped ceramics continues to pose a formidable challenge, leaving them far away from photonic application. Here, to fill this important gap, the demonstration of Tb doped transparent ceramics for luminescent thermometric windows is reported. Y2Zr2O7:Tb (YZO:Tb) ceramics are used as an illustrative example. After a sequence of thermal treatments, the defect centers F/F+ and defect clusters [Tb-Y(4+)-O2--Tb-Y(4+)] and [Tb-Y(4+)-e(center dot)] in these YZO:Tb transparent ceramics are eliminated, resulting in a notable enhancement of their in-line transmittance from 71% to 76%, making it close to the theoretical limit. Moreover, the corresponding photoluminescence increased significantly, reaching a factor of 296 times. Furthermore, a temperature feedback window is designed using the excitation intensity ratio (EIR) or single-band luminescence intensity ratio (SBLIR) mode, which presents high sensitivity (1.04%) and high repeatability (98%). This work not only provides a paradigm in the application of the Tb doped transparent ceramics for temperature sensing windows, but also suggests a pathway to build efficient thermometers based on excited state population deployment in window systems.