Influence of Nd3+ concentration on mid-infrared emission in PbF2 crystal co-doped with Ho3+ and Nd3+ ions
Yan Chen, Juncheng Tan, Peixiong Zhang, Weibi Zheng, Lin Li, Lianhan Zhang, Zhen Li, Yin Hang, Zhenqiang Chen
Abstract
A promising series of Ho y Nd x Pb (1– x – y ) F 2 ( x = 0, 0.01, 0.02, 0.03, 0.04; y = 0.02) crystals was grown by the Bridgman method . The influence of the Nd 3+ ions concentration on mid-infrared (∼2.0, ∼2.9 and ∼3.9 μm) fluorescence emissions of Ho 3+ ions in the PbF 2 crystal excited by 808 nm laser diode was investigated in this work. The energy transfer mechanism between Nd 3+ ions and Ho 3+ ions under different concentrations of the Nd 3+ ions was systematically analyzed. The results show that the Nd 3+ ions have good sensitization and deactivation effect on the Ho 3+ ions to stimulate the mid-infrared fluorescence emissions . The experimental analysis proves that the sensitization efficiency of the Nd 3+ ions is relatively stable at around 93.45% with varying Nd 3+ -doping concentrations. Concentration dependence studies indicate that the concentration of the Nd 3+ ions has significant influence on mid-infrared emissions. When the doping concentration of the Nd 3+ ions is up to 2.0 at%, the intensity of ∼2.0, ∼2.9 and ∼3.9 μm emissions all reach the maximum. The output characteristics of a 3.9 μm laser are simulated, and it is found that with the increase of the Nd 3+ -doping concentration, the peak power, pulse width, and peak energy all meet the trend of first increasing and then decreasing, and Ho 0.02 Nd 0.02 Pb 0.96 F 2 crystal displays the best performance. All the results show that the Nd 3+ /Ho 3+ co-doped PbF 2 crystals might act as a useful optical medium for mid-infrared laser applications.