渐变折射率薄膜纳秒激光损伤演化特性研究

Gradient-index thin film is a kind of optical thin film whose refractive index varies continuously with its thickness. This special kind of films demonstrates the advantages of improved adhesion, reduced optical losses and internal stress in practice. Recent researches show that the gradient-index thin films also have very promising potentials in improvement of resistance to laser induced damage. Due to composite mixture and interface coupling mode, the laser induced damage property of gradient-index thin film is different from the conventional coating. The laser induced damage mechanism of gradient-index thin film has been investigated by researchers. However, the nanosecond laser induced damage evolvement mechanism of gradient-index thin film interface coating is still unclear. Our research will be focused on the nanosecond laser induced damage evolvement property of gradient-index thin film. The effect of mixture system and quasi-continuous interface coupling on laser damage evolvement property will be investigated. The enhancement of laser damage resistance will be analysis by experiment characterization and theoretical modeling. Based on laser induced damage test, we will carry on the in-situ analysis the connection between mixture and interface coupling mode by laser induced damage evolvement process, which will be helpful to exploring mechanism of LIDTs on gradient-index thin film.

渐变折射率薄膜其特有的折射率沿着膜厚逐渐变化的特性，平滑膜层间材料热物性参数之间的跃变，在提高薄膜附着力、减少残余应力、提升薄膜抗激光损伤能力等方面有着理想的应用前景。材料混合方式及界面体系的耦合方式的不同，渐变折射率薄膜表现出与常规薄膜所不同的激光损伤特性，目前对于渐变折射率薄膜激光损伤特性的研究处于起步阶段，许多机理性的问题还没有得到深入的研究。本课题针对此研究现状，着眼于纳秒激光作用下渐变折射率薄膜损伤演化规律，以及材料混合体系与准连续界面体系的耦合方式对渐变折射率薄膜纳秒激光损伤特性演化的影响开展研究。通过实验表征和理论建模分析渐变折射率薄膜抗激光损伤能力增强因素及薄弱环节，结合激光损伤实验获取薄膜体系在激光作用下的特性演化信息；建模分析材料混合参数及界面体系对渐变折射率薄膜激光损伤特性演化的影响，获取薄膜体系设计和激光损伤演化特性关联信息，探索渐变折射率薄膜纳秒激光诱导损伤机制。

面向应用于超高功率激光系统中的薄膜类光学元件超高损伤阈值的需求，发展新型高功率光学薄膜制备体系及研究新型光学薄膜在激光辐照下的抗损伤能力对整个激光系统的输出功率有着重要的意义。渐变折射率薄膜其特有的折射率沿着膜厚逐渐变化的特性。平滑膜层间材料热物性参数之间的跃变，在提高薄膜附着力、减少残余应力、提升薄膜抗激光损伤能力等方面有着理想的应用前景。本课题基于宽光谱监控的离子束溅射双元靶的精确制备技术完成混合材料体系与不同界面体系样品的制备。利用超快激光泵浦探测技术、正电子湮没技术等多种分析技术揭示了混合材料体系与准连续界面体系在激光作用下的损伤机制，获取了具备指导意义的薄膜体系设计参数。从实验和理论解析了渐变折射率（准连续界面）薄膜的抗激光损伤增强的基本原理及演化规律，创新性地建立了基于准连续界面特性的损伤抑制的基本模型。