黄光波段新型Tb3+自激活激光晶体的探索研究

Due to the advantages of high output beam quality, stable performance and long operation lifetime, solid-state lasers operating in visible band can be widely used in many applications, such as optical data storage, color display, biomedical and submarine communication, etc. Blue-diode-pumped laser crystals singly-doped with Pr3+, Sm3+ or Dy3+ has been considered as a favorable method for directly obtaining a simple and compact visible solid-state laser. However, limited by the visible laser operating mechanisms of above rare earth ions, the used host materials at present in which high efficient visible laser operation can be realized are mainly the fluoride crystals with harsh growth conditions and high cost. Furthermore, the high performance yellow laser around 580 nm has not still been realized in the laser crystals doped with above rare earth ions. This project plans to use Tb3+ as a new active ion to remove some restrictions of the existing visible laser operating mechanisms on the host materials. We will search for some borate and phosphate crystals with loose growth conditions and weak crystal field strength as host materials, and then carry out the researches about the growth of Tb3+ self-activated crystals and their yellow laser performances. On the basis of solving the weak absorption at the pump light and growth difficulty of the crystal with high doping concentration, some new type of high performance laser crystals operating in yellow band will be developed.

可见波段固体激光具有输出光束质量高、性能稳定、工作寿命长等优点，广泛应用在光学数据存储、激光打印、彩色显示、生物医学以及海底通讯等领域。利用蓝光波段半导体激光泵浦Pr3+、Sm3+或Dy3+单掺的激光晶体，已经成为一种直接获得紧凑坚固的可见波段固体激光器的有效方法。然而受限于上述稀土离子可见波段激光的运转机制，目前能实现该波段激光高效运转的基质材料主要是生长条件苛刻和成本较高的氟化物晶体。另外，在上述稀土离子掺杂的激光晶体中也还未能实现580nm波段黄色激光的高性能运转。本项目计划采用Tb3+作为新型激活离子，解除现有可见波段激光运转机制对基质材料的若干限制因素，筛选一些生长条件宽松且晶场强度较弱的硼酸盐和磷酸盐晶体作为基质材料，开展Tb3+自激活激光晶体的生长及其黄光波段激光性能研究，在同时解决对泵浦光吸收弱和高掺杂浓度晶体生长困难的基础上，开发出新型的高性能黄光波段激光晶体。

黄光波段固体激光器具有输出光束质量高、传输距离远、性能稳定等优点，而且器件坚固耐用、紧凑可靠，可应用于彩色显示、生物医学、天文学以及光谱学等领域。利用蓝光波段激光泵浦Tb3+掺杂晶体，已经成为一种直接获得紧凑坚固的黄光波段固体激光器的有效方法。本项目分别采用提拉法和熔盐法首次成功生长获得了四种具有较弱荧光浓度猝灭效应、易于生长并具有较佳物化性能的新型Tb3+自激活激光晶体Sr3Tb2(BO3)4、Li6Tb(BO3)3、TbAl3(BO3)4和NaTb(WO4)2，并开展了晶体结构组成与黄光波段发光性能间相互关系的综合研究。上述自激活晶体在488nm泵浦波段处的吸收系数均远高于现有的Tb3+掺杂激光晶体，有效解决了Tb3+离子在488nm泵浦波段吸收截面小从而严重制约Tb3+激光性能的瓶颈问题。同时，上述晶体具有较大的黄光波段荧光分支比和发射截面，而且黄光发射波段比较宽且平坦，覆盖到了具有重要应用价值的钠黄光波长589nm，有望成为黄光波段，特别是589nm激光输出的潜在增益介质。另外，针对现有488nm波段高功率泵浦源结构复杂、体积较大且价格昂贵的问题，本项目提出了一种创新性的黄光波段激光运转机制，解决了现有Tb3+固体激光无法采用商品化高功率450nm波段半导体激光器作为泵浦源的问题，能够有效降低泵浦光源的成本，并有望提高Tb3+固体激光的输出性能。本项目共发表SCI论文8篇，申请中国发明专利2项（其中一项已授权），培养毕业博士研究生3名。