Tm3+ Modified Optical Temperature Behavior of Transparent Er3+-Doped Hexagonal NaGdF4 Glass Ceramics

Er3+-doped and Er3+-Tm3+-co-doped transparent hexagonal NaGdF4 glass ceramics are fabricated via melt-quenching method. The emissions of Er3+-doped NaGdF4 glass ceramics are adjusted from the green to red by varying the concentration of Tm3+ 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 Er3+-doped NaGdF4, which shifts toward the lower temperature range by co-doping with Tm3+ 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 Er3+-doped NaGdF4 glass ceramics. Moreover, the relative sensitivity SR is proved to be dependent on the pump power of 980-nm lasers in Er3+-doped NaGdF4 and Er3+-Tm3+-co-doped NaGdF4.