Thermometry strategy developed based on fluorescence contrast driven by varying excitations in codoped LiNbO3

We propose what we believe is a novel optical thermometry strategy(FIR-Ex)based on the fluorescence intensity ratio(FIR)between two radiations associated with the same emission peak but different excitation wavelengths,in contrast to the traditional approach(FIR-Em),which depends on the FIR at varying emission wavelengths.The temperature-dependent FIR within the FIR-Ex strategy arises from the different charge/energy evolution routes,rather than the distribution of thermally coupled levels within the FIR-Em strategy.Considerable diversity in thermal behaviors and luminescence mechanisms was demonstrated by analyzing the 618 nm red emission in Pr^3+-doped congruent LiNbO3(Pr:CLN)under 360 and 463 nm excitations.The temperature sensitivity was further improved via Mg^2+ codoping due to the optimization of charge dynamics and energy transfer processes.Given its wide detection scope,relatively high absolute sensitivity at low temperature,and high tunability of temperature sensitivity,the FIR-Ex strategy is promising for developing optical temperature-sensing materials with high performance.