高阈值超宽带激光薄膜色散优化设计与损伤机制研究

Improving the laser output enregy and compressing the pulse width are two aspects to enhance the peak power of laser system. In order to obtain transform-limited pulse or few-cycle pulse, it requires the high threshold, ultrabroadband and the free regulation of dispersion at the same time, which bring new challenges to science and technology of laser coating. However, the above three aspects are isolated to study mostly and have not been balanced together. This project focuses on researching the damage mechanism of ultrabroadband dispersion coating and the problem bescause of ultrabroadband restricting high damage threshold and the dispersion. For ultrabroadband dispersion coating with high damage threshold, the new design method and structural evaluation model will be proposed firstly. At the same time, the relationships among broadband, high reflectivity, amount of dispersion compensation and high damage threshold will be determined and quantized. Then, we will study the electric field distribution mathematical model of material. And the precise control technology of sensitive film thickness will be formed. Based on material properties, standing wave field, multi-wavelength mechanism, nonlinear effects and so on, the damage mechanism of ultrabroadband laser coatings will be carried out.The electric field structure and material properties evaluation parameters will be introduced. Based on the above work, the solving approach of dispersion control and laser induced damage caused by ultrabroadband will be obtained.

提升激光峰值功率的主要手段有两个方面，即提高系统输出能量和压缩脉冲宽度。实现脉冲宽度压缩至变换极限或周期量级，对薄膜科学与技术提出了新的要求：同时须满足高阈值、超宽带及色散自由调控，但是目前的报道更多的是将这三者孤立开展，三者兼顾的研究还没有系统的进行。本项目拟研究超宽带对高损伤阈值和色散调控的制约问题及超快超宽带色散薄膜的损伤机制。首先提出超宽带新型高阈值色散调控薄膜的设计方法和结构评价模型，明确和量化宽带、高反射率和色散补偿量及色散振荡要求与高损伤阈值之间相互制约的关系，研究薄膜材料电场分布调控的数理模型。此外，形成敏感膜层厚度精确控制技术，并基于材料特性、驻波场、多波长机制、非线性效应等，开展超快超宽带色散薄膜的损伤机理研究，引入电场结构和材料性质评价参数，获得超宽带给色散调控和抗激光损伤能力带来的约束问题的解决途径。

提升激光峰值功率的主要手段有两个方面：即提高系统输出能量和压缩脉冲宽度，实现脉冲宽度压缩至变换极限或周期量级，对薄膜科学与技术提出了新的要求：同时须满足高阈值、 超宽带及色散自由调控。本项目主要研究超宽带对高损伤阈值和色散调控的制约问题及超宽带色散薄膜的损伤机制。.我们基于谐振效应和多类对称腔初始结构，将薄膜的色散补偿能力提高到一个新的水平，在750-850nm宽带范围内，设计和制备的色散调控量达到1000fs^2；创新性结合了四分之一波长和共振腔的膜层初始设计结构，获得了-20,000 fs^2的大色散量，实现从2.8 ps到213 fs的激光脉冲压缩，为超快激光系统中实现精确的色散补偿和简化啁啾脉冲放大系统提供了一种新的途径。.基于啁啾膜系结合超低折射率SiO2膜层匹配入射介质（空气）阻抗从而减小色散振荡这一设计思想，设计了雕塑结构低振荡色散镜，能在680-920nm波长范围内提供平坦的-200fs^2色散调控量。基于激光脉冲与多层介质薄膜作用时，精确控制入射角度改变引起的脉冲在每一膜层反射和透射相位变化，创新设计得到了色散补偿量随入射角度调谐的超快激光色散薄膜，实现了压缩脉宽的连续可调节，克服了传统薄膜无法调谐色散补偿量的缺点。.对飞秒作用下特殊的鼓包损伤结构进行研究，利用压力驱使模型，基于鼓包形成和演化，初步获得了色散镜的损伤机制模型。提出了超宽带新型高阈值色散调控薄膜的设计方法和结构评价模型，明确和量化宽带、高反射率和色散补偿量及色散振荡要求与高损伤阈值之间相互制约的关系，基于优化材料特性和驻波场分布，提出了金属介质膜和啁啾结构宽带高反射高阈值低色散镜结构及其设计方法，获得了宽带高阈值低色散镜，并明确了材料特性和电场调控相结合是解决超宽带给色散调控和抗激光损伤能力带来的约束问题的根本途径。.项目执行过程中共发表学术论文10篇，其中SCI收录6篇，EI收录4篇，影响因子大于3 的论文2篇，申请发明专利3项。项目圆满完成预期成果与技术指标。