Achieving Efficient Optical Thermometry in Terbium‐Doped Highly Transparent Ceramics

Abstract 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. Y 2 Zr 2 O 7 :Tb (YZO:Tb) ceramics are used as an illustrative example. After a sequence of thermal treatments, the defect centers F/F + and defect clusters [] and [] 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.