Excitation powder dependent optical temperature behavior of Er3+ doped transparent Sr0.69La0.31F2.31 glass ceramics

The knowledge of the pump power for which the population of thermally coupled energy levels (TCL) changes with power increase is of valuable importance for optical temperature sensors. In this paper, novel Er3+ doped transparent Sr0.69La0.31F2.31 glass ceramics was fabricated successfully, and its structure is studied by XRD, TEM and HRTEM analyses. The H-2(11/2)/S-4(3/2), F-4(9/2(1))/F-4(9/2(2)), and I-4(9/2(1))/I-4(9/2(2)) levels of Er3+ are proved as TCL by analyzing the temperature dependent fluorescence intensity ratios. The spectrum split, thermal quenching ratio, population stability, and temperature sensitivity from three TCL are observed to be dependent on the pump power. A new fitting method has been developed to establish the relation between fluorescence intensity ratios and temperature. It is found that the combined use of H-2(11/2)/S-4(3/2), F-4(9/2(1))/F-4(9/2(2)), and I-4(9/2(1))/I-4(9/2(2)) as thermally coupled energy levels will get a more precise temperature reading from 62.7 K to 800 K with the help of low excitation power at 66.8 mW/mm(2). (C) 2016 Optical Society of America