YAB晶体中Yb3+到Er3+的能量传递

1.55 μm波段是光通讯的一个重要波段,而且对人眼安全,有高的大气透过率,因此可以广泛应用于通讯和遥感测距等领域。由于Er³⁺离子对商品化的InGaAs激光二极管的抽运波长不能有效吸收,因此一般通过在基质中共掺杂Yb³⁺和Er³⁺离子来获得1.55 μm波段激光输出。采用助熔剂法生长了不同Yb³⁺和Er³⁺掺杂浓度的YAl₃(BO₃)₄(YAB)晶体。运用速率方程模型研究了晶体中Yb³⁺到Er³⁺能量传递过程,得到了根据Yb³⁺离子的荧光寿命计算能量传递系数的简单计算公式。计算了不同掺杂离子浓度的YAB晶体中的能量传递系数等相关参数。结果表明,在YAB晶体中,Yb³⁺到Er³⁺能量传递非常有效,YAB晶体可以作为一种能获得1.55 μm激光输出的良好介质材料。

The Energy Transfer from Yb3+ to Er3+ in YAl3(BO3)4 Crystal

The laser emission around wavelength at 1.55 μm is located in the "eye-safe" region and plays an important role in the optical communication and remote sensing. However, Er3+-doped materials cannot be efficiently pumped by the InGaAs laser diodes because of the lower absorption of Er3+ at the wavelength of 976 nm. Generally, the solution is to add Yb3+ ion as a sensitizer to improve the pumping efficiency. So, in the Yb3+ and Er3+ co-doped materials, the pumping energy can be efficiently absorbed by Yb3+ and transferred to Er3+. In this paper, YAl3(BO3)4 crystals with different Yb3+ and Er3+ doping concentrations were grown by the flux method. The Yb3+ to Er3+ energy transfer in YAB crystals was investigated with the rate equation without considering the back energy transfer and up-conversion processes. The simple formulation for calcula-ting the energy transfer coefficients was derived according to the fluorescence lifetimes of Yb3+ ion. The energy transfer parameters were also calculated. The results showed that the energy transfer is very efficient in the YAB crystal and the energy transfer probabilities from Yb3+ to Er3+ increases with the increasing of Yb3+ concentrations. The energy transfer coefficients calculated by using experimental data are accordant with those calculated by theory, it means that the formulation is suitable for calculating the energy transfer coefficient in the high phonon energy materials. The energy transfer coefficients and critical interaction distance are comparable with or higher than those in other materials, which means that the energy transfer from Yb3+ to Er3+in YAB crystal can be more efficient. So, this host could be a good candidate for the 1.55 μm laser media.