低浓度Ho3+掺杂BaxSr1-xF2中红外单晶光纤的制备与3.9μm激光性能研究

稀土钬离子(Ho3+)的3.9μm激光工作在高透过率的中红外“大气窗口区”，在红外对抗、激光制导、环境监测等领域具有重要应用，但现阶段仍缺乏成熟的3.9μm波段Ho3+掺杂激光材料。本项目针对Ho3+的3.9μm激光量子亏损高、激光通道阻塞和热效应严重的共性问题，提出以低声子能量的Ho3+:BaxSr1-xF2混晶(其中x=0~1)为研究对象，利用Ho3+在BaxSr1-xF2中的“局域团簇”增强Ho3+离子间上转换效率，在低浓度掺杂条件下突破激光通道阻塞，实现高效率3.9μm连续模式激光输出；同时，将Ho3+:BaxSr1-xF2制备成单晶光纤的形态，进一步提高应对热效应的能力。本项目一方面创建Ho3+的3.9μm激光发射过程的物理机制，另一方面通过高通量制备进行Ho3+:BaxSr1-xF2单晶光纤的组分筛选，有望实现3.9μm激光性能的突破，对中红外激光材料的发展具有重要意义。

The 3.9μm laser emission of Ho3+ covers the mid-infrared "atmospheric window" of the highest transmittance, thus is of significant importance in applications such as IR countermeasure and laser guided missile. However, the 3.9μm laser performance of currently available Ho3+ doped materials are still far from applicable. In order to overcome the conventional problems of Ho3+ doped 3.9μm laser materials, such as huge quantum loss, self-terminating of laser transitions and serious thermal problems, we propose to use low-phonon-energy compound Ho3+:BaxSr1-xF2 to achieve efficient continuous-wave laser emission at 3.9μm by taking advantage of "clustering" behavior of Ho3+ in BaxSr1-xF2, which can increase the efficiency of energy transfers between Ho3+ even in lightly doped Ho3+:BaxSr1-xF2. On the other hand, higher 3.9μm laser output power is expected by fabricating Ho3+:BaxSr1-xF2 into the form of single crystal fibers to achieve better thermal dissipation. Efforts will be proposed to develop the energy transfer mechanisms of the 3.9μm laser processes in Ho3+. On the other hand, the chemical composition of Ho3+:BaxSr1-xF2 for 3.9μm laser will be optimized with the help of “high-throughput synthesis” of single crystal fibers using “Numerous Microchannel Crucible” technique. In the framework of this research project, new progresses of 3.9μm laser performance in Ho3+ doped laser materials are expected, which will be of significant importance for development of Ho3+ doped mid-infrared laser materials.