Precise determination on the upconversion processes of the ultraviolet upconversion fluorescence of Ho³⁺-doped Y₂O₃ ceramic by excitation of a 532-nm continuous-wave laser

Aiming at developing a Ho³-based continuous-wave ultraviolet laser, the method of determining the weight of the excited-state absorption (ESA) process occupied in the populating of the ³D₃ level is studied. Using the rate equation model, the weight is found to be related to the weighting factors of the double-exponential decay components of the ³D₃ level. Using time-resolved spectroscopy, the weight of the ESA process for Y₂O₃ ceramic doped with 0.1 mol. % Ho³ is experimentally determined to be 83%. Furthermore, the fluorescence dynamic properties of the Ho³-doped Y₂O₃ ceramic with different doping concentrations were analyzed, and the weight was found to decrease with the doping concentration but by no less than 70%.