二极管抽运的紧凑型高功率固体激光器在光电对抗、激光软硬杀伤、激光点火核聚变、同位素分离等领域具有广泛的应用前景。高功率激光系统对增益介质材料的热力学性能提出了较高的要求。硅酸钪晶体具有负热光系数dn/dT（-6.3×10-6 K-1）、热学性能佳κ（7.5 W·m-1·K-1）的特征。本申请项目通过设计镱离子与晶体场的强场耦合作用，初步生长获得具有大的下能级分裂（1027 cm-1）的掺镱硅酸钪晶体，可有效缓解能级通道中的热阻塞效应，并初步实现低阈值高功率准四能级激光输出。基于以上结果，本项目首次提出掺镱硅酸钪晶体及其复合结构晶体作为研究对象，系统性地掌握掺镱硅酸钪激光晶体参数、光学性能、热力学特性和激光特性，为掺镱硅酸钪激光晶体作为高功率固体激光增益介质的可行性提供支撑数据。本申请项目的开展，有望为低阈值高功率固体激光领域的增益介质研究开拓新的方向。

Laser diode pumped high power solid state laser is widely employed in the areas of Optoelectronics Countermeasure, Laser Fusion Ignition and Isotope Separation. High power laser system has high requirement on thermal and mechanical properties of laser gain materials. Sc2SiO5 crystal possesses high thermal conductivity (κ = 7.5 W·m-1·K-1） and minus colarescence coefficient (dn/dT = -6.3×10-6 K-1）. By strong coupling between ytterbium ions and crystal field, quasi-four level Yb:Sc2SiO5 single crystal were grown with large energy stark splitting (1027 cm-1) which is beneficial for releasing thermal block during high power laser operation. Encouraged by primary realization of low threshold and high power laser based on Yb:Sc2SiO5 gain crystal, we propose large sized and bonded Yb: Sc2SiO5 crystal with the advantage of thermal compensation for high power laser operation. The thermal and mechanical properties of Yb:Sc2SiO5 crystal in high power laser system will be systematically studied. The proposal aims to offer important supporting data for building up new type of high power solid state laser based on Yb:Sc2SiO5 gain crystal. The project is expected to open a new research direction of quasi-four-level gain materials for low threshold and high power laser system.