基频吸收氟磷酸盐玻璃的瞬态缺陷诱导激光损伤机理与性能调控研究

The UV laser induced damage of fused silica optics and the deficiency of present color separation technique have become key limiting factors restricting the high flux output and stable operation of the inertial confinement fusion (ICF) laser devices. The development of novel color separation optics with higher UV laser induced damage threshold for color separation principle innovation will open up new paths to solve the above problem. On the basis of the preliminary study on the fundamental frequency absorption fluorophosphate glasses, this project attempts to establish the microstructure model and the intrinsic defects formation mechanism for the fluorophosphate glass with high damage threshold, based on the understanding of the microstructure characteristics of the material. Based on the pump-detection ultrafast technique and the transient spectrum technology, the project focus on studying and analyzing the transient process and physical mechanism of laser induced damage from the perspective of real-time variation of micro-defects, in order to obtain the transient evolution of material structure and micro-defects and its influence on dynamic changes of optical properties of the material, and to establish the mechanism and model of its laser damage induced by transient defects, and finally to control and optimize the material’s laser induced damage resistance and fundamental frequency absorption ability. The research results of this project can provide theoretical and technical support for the development of new fundamental frequency absorption separation optics and their engineering applications, which are of great importance for promoting the development of ICF high power laser driver technology.

熔石英元件的紫外激光损伤和谐波分离技术的局限性，已成为制约惯性约束聚变激光装置能量提升和稳定运行的主要因素。研发具有更高紫外损伤阈值的新型谐波分离元件，革新谐波分离技术原理，将为解决上述问题开辟新路径。在对氟磷酸盐玻璃基频吸收特性的前期探索基础上，本项目基于对氟磷酸盐玻璃材料微观结构特性的认识，建立高损伤阈值基频吸收氟磷酸盐玻璃的微观结构模型，揭示本征缺陷形成机理；重点基于泵浦-探测超快技术和瞬态光谱技术，研究从材料微观缺陷角度分析激光诱导损伤的瞬态过程与物理机理；获得材料结构和微观缺陷瞬态演化机制及材料光学特性动态变化规律，建立瞬态缺陷诱导材料激光损伤机理；并对材料的抗激光损伤性能和基频谐波分离能力进行优化设计与调控。本项目研究成果可为研发新型基频谐波吸收分离元件及其工程应用提供理论和技术支撑，对促进ICF高功率激光驱动器技术发展具有重要意义。

项目开发出的系列氟磷酸盐玻璃为有效解决ICF终端光学组件中熔石英元件的谐波分离技术局限以及三倍频紫外激光诱导损伤的瓶颈问题提供了一种新的途径。本项目以揭示基频（1053nm）吸收低含氟磷酸盐玻璃的激光诱导损伤机理为基本目标，从材料的微观层面出发，首先对不同玻璃组成和制备工艺下的基频吸收氟磷酸盐玻璃进行表征，获得了基频吸收氟磷酸盐玻璃的微观结构特征和本征缺陷形成机理。.其次，运用泵浦-探测超快和瞬态光学与光谱技术，实验研究了高能紫外激光与基频吸收玻璃相互作用过程中，材料的瞬态吸收变化、由特定本征缺陷引发荧光的实时衰减情况以及玻璃网络结构的变化情况，阐明了瞬态缺陷的产生、缺陷演化机制、缺陷导致材料光学特性发生的动态变化。研究结论可为揭示基频吸收氟磷酸盐玻璃的激光诱导损伤机理提供有益的理论指导。.继而，借助于时间分辨阴影成像技术，实验研究了由高能纳秒紫外激光引发基频吸收氟磷酸盐玻璃的初始体损伤、损伤增长规律、损伤动力学过程，获得了基频吸收玻璃的激光诱导损伤阈值、损伤增长因子以及包括冲击波的传播、粒子物的喷溅、裂纹的延伸在内的动态过程。.最后，揭示了基频吸收氟磷酸盐玻璃的高能紫外激光诱导损伤机理；基于损伤机理，改变玻璃的制备工艺，验证通过优化制备工艺籍以进一步提升基频吸收氟磷酸盐玻璃抗激光损伤性能的可能性。结果表明，改变玻璃的制备工艺能够明显影响材料中部分本征缺陷的含量，继而引起玻璃对入射紫外高能激光的吸收特性发生改变，最终因本征缺陷含量的变化使得基频吸收氟磷酸盐玻璃的抗激光损伤性能得到进一步提升。.本项目揭示的基频吸收氟磷酸盐玻璃的激光诱导损伤机理以及证实的基频吸收氟磷酸盐玻璃抗激光损伤性能的提升方案，能够为进一步开发出可作为ICF终端光学组件中新型色分离紫外光学元件提供理论指导与技术支持。