Tm(3+) Modified Optical Temperature Behavior of Transparent Er(3+)-Doped Hexagonal NaGdF4 Glass Ceramics.

Er(3+)-doped and Er(3+)-Tm(3+)-co-doped transparent hexagonal NaGdF4 glass ceramics are fabricated via melt-quenching method. The emissions of Er(3+)-doped NaGdF4 glass ceramics are adjusted from the green to red by varying the concentration of Tm(3+) ion under the excitation of 980 nm. The spectrum, thermal quenching ratio, fluorescence intensity ratios, and optical temperature sensitivity of the transparent glass ceramics are observed to be dependent on the pump power. The maximum value of relative sensitivity reaches 0.001 K(-1) at 334 K in Er(3+)-doped NaGdF4, which shifts toward the lower temperature range by co-doping with Tm(3+) ions, and has a maximum value of 0.00081 K(-1) at 292 K. This work presents a method to improve the optical temperature behavior of Er(3+)-doped NaGdF4 glass ceramics. Moreover, the relative sensitivity SR is proved to be dependent on the pump power of 980-nm lasers in Er(3+)-doped NaGdF4 and Er(3+)-Tm(3+)-co-doped NaGdF4.