Optical temperature sensing of Er³⁺/Yb³⁺-doped PSN-PMN-PT crystal based on temperature-dependent upconversion luminescence

The optical temperature sensing of Er3+/Yb3+-doped Pb(Sc1/2Nb1/2)O3 (PSN)-Pb(Mg1/3Nb2/3)O3 (PMN)-PbTiO3 (PT) (6PSN-61PMN-33PT with 2- wt% Er2O3 and 2- wt% Yb2O3) crystal was investigated based on temperaturedependent upconversion luminescence. Apparent difference in variation of luminescence intensity with temperature was observed for different emission bands. Moreover, excellent relative sensitivity and comparable absolute sensitivity were demonstrated based on the thermally coupled levels (2H11/2 and 4S3/2) and nonthermally coupled levels (4S3/2 and 4F9/2), respectively. These findings hold substantial implications for promoting the development of ferroelectric crystals towards electric-optical integration.