共掺离子对掺钕氟化锶激光晶体的团簇结构影响及其物理机制研究

High-repetition-rate high-power ultrafast laser is the latest frontier of international laser technologies. It is the technological high point which attracts the world's attention to dedicate, chase and compete. As one of the key factors, it is urgent to develop new laser gains with high thermal conductivity and broadband photoluminescence. The neodymium-doped alkaline earth fluoride crystal has excellent comprehensive properties, and the spectral and laser performance could be manipulated by codoping of Y3+, La3+ and Gd3+, which is considered as a potential candidate for generation of high-repetition-rate ultrafast lasers. The project focuses on the rare earth clusters study in neodymium doped SrF2 crystal. The first principles calculation and synchrotron radiation x-ray absorption fine structure were utilized to study the influence and manipulation of neodymium clusters by codoping of Y3+, La3+ and Gd3+ ions, and the related mechanisms. Taking the artificial designing of new crystals into consideration, the manipulated lanthanide clusters were combined with the characters of the photoluminescence, and a qualitative or semi-quantitative physical model of the composition, rare earth clusters and photoluminescence properties would be established. The solid support of designing and accelerating the development of new high-repetition-rate high-power ultrafast laser crystals was expected.

重频高功率超快激光是国际激光技术的最新研究前沿，而发展兼具高热导率和宽光谱特性的新型激光增益介质是其关键核心之一。掺钕碱土氟化物晶体综合性能优异，通过共掺Y3+、La3+、Gd3+等离子，可以实现光谱和激光性能的调控，被认为有潜力实现重频超快激光输出。然而，共掺离子的调控机制尚不明确，本项目以掺钕氟化锶晶体为研究对象，第一性原理计算和同步辐射XAFS谱联立解析稀土离子团簇结构，研究共掺离子Y3+、La3+、Gd3+对激活离子Nd3+团簇结构的影响及其物理机制，获得共掺离子调控激活离子团簇结构的规律性认识。在此基础上，结合Nd3+:SrF2晶体光谱性能随共掺离子种类、掺杂浓度等的变化特征，建立钕离子掺杂氟化锶晶体组分构成、团簇结构与光谱性能的定性或半定量关系模型，在一定范围内实现激光晶体材料的人工设计和按需定制，面向重频高功率超快激光技术，为新型激光晶体材料的探索和加速研制提供理论支撑。

面向重频超快激光技术发展新需求，本项目系统开展了Nd,R:SrF2激光晶体的团簇结构、光谱性能及其相互关系的研究工作，主要取得了以下三个方面的进展：（1）研究发现了三价稀土离子掺杂碱土氟化物晶体立方亚晶格和四角反棱柱结构团簇相对稳定性判据及其演化特征，为该类晶体材料的组分/结构设计提供了有力保障。（2）研究厘清了共掺离子Y、La、Gd对钕离子团簇结构特征的影响，揭示了晶格畸变和静电作用耦合竞争决定了团簇结构特征，从电子结构层面进一步指出，键的杂化强度决定了该结构特征。（3）研究明确了Nd,R:SrF2晶体团簇结构与光谱性能的对应关系，结合晶体组分与结构，初步建立了Nd,R:SrF2晶体组成、结构与光谱性能的相互关系，为新型宽光谱激光材料的研发提供了参考和指导。本项目申请发明专利1项，并已获得授权；发表标注受本项目资助的SCI论文16篇；招收、培养研究生3名。