柔性可调谐微纳结构光学元件的研制与性能表征

Surface relief micro/nanostructures that are capable of optical wave front modification are implemented in micro optical components to alter the phase of the light propagating through them. The micro/nanostructures are usually structurally rigid and non-deformation by external stimuli due to the durable and non-deformable substrates’ materials, such as glass, fused silica, quartz et al. The deformable and adaptive optics are desired to allow real-time optimization of their optical performance and has emerged as an exciting research area in micro-optics. Shape memory polymer (SMP) can be used to fabricate tunable micro-optical components with the shape recovery ability to switch between as-fabricated and programmed micro/nanostructures. Through analysis of various match functional materials, the SMPs with suitable glass transition temperature and superior optical characteristics are chosen as flexible base materials. Through properly adjusting selection of materials’ reasonable ratio, the modified SMP possesses high transparency, good toughness, adjustable glass transition temperature, easy to forming. The flexible and tunable micro-optical components with micro/nanostructures are designed and developed, and the corresponding tunable deformation mechanism is studied by the thermodynamic theory and simulation analysis. By optimized the processing technique of surface micro/nanostructures, various tunable micro-optical components with programmable surfaces micro/nanostructures are prepared by facile pouring and hot embossing process. A measurement system for testing the optical properties of the tunable micro-optical components is designed and built. The materials performance’s conversion and the forming and developing of the micro/nanostructures, are investigated during the preparation and tunable process. The relationship between the deformation ability of micro/nanostructure and optical property response is demonstrated. Facile lithographic replication and suitable materials offer exciting opportunities for the fabrication of flexible and tunable micro-optical devices to promote the development of adaptive photonic devices.

材料表面微纳结构能够对光进行调制和变换，从而实现光波发射、传输、变换和接收等功能，可应用于多种微光学元件的设计与制备。传统硅基等材料表面微纳结构受到基体材料性质的限制，无法在外界驱动下发生变形，光学性能单一，不能满足微光学领域对光学性能可调控的进一步应用需求。本项目选择具有形状回复能力的形状记忆聚合物(SMP)材料作为柔性衬底，通过合理的材料改性，提高材料的可加工性、光学透明度；优化制备工艺参数，结合光刻技术、浇筑成型和纳米热压印工艺构筑多种可灵活变形的SMP表面微纳结构，实现程序化控制光学性能的功能；进行可调谐微纳结构光学元件的设计和研制，对相应的工作机理进行热力学理论和变形仿真分析；设计搭建可调谐微光学元件的光学性能检测系统，研究制备和调谐过程中的材料性能转换与微纳结构的形成和演化，分析表面微纳结构的变形特性和光响应规律，为设计和制备柔性可调谐微光学器件提供有利的理论和实验支撑。

形状记忆聚合物（SMP）具有良好的变刚度特性、回复变形能力、光学性能可调、易于加工成型、成本低等优点，是构建具有可调谐光学特性的柔性微纳光学元件的理想材料。研制特定的功能性微光学元件并充分认识SMP表面微纳结构的相关物理特性和驱动可调谐变化规律具有重要的科学意义。本项目通过优化配比、合理改性制备了具有优异热力学性能、形状记忆效应和光学性能的SMP基柔性薄膜衬底，有效提升了柔性光学衬底材料的光学性能、器件加工和驱动变形能力。根据理论仿真优化结果，在SMP柔性薄膜表面设计制备了高精度的微纳圆锥阵列二元结构，通过对微纳结构变形的灵活驱动控制，可实现柔性减反射薄膜的自适应可擦除调谐功能。该柔性薄膜元件对可见光波段反射率可从4.5%到0.6%自由快速转换。进一步，项目组为了拓宽柔性光学元件的应用范围，开展多功能光学元件的研制，我们设计合成了具有优异荧光特性和选择性吸附能力的多孔超薄氮化碳功能纳米片，发展了多种有害污染物的荧光检测体系。配合刺激响应性SMP柔性基体材料，通过可见光激发，成功制备具有可调控荧光发光特性的多功能柔性光学薄膜，在荧光检测、催化降解等多个领域具有很好的应用潜力。在项目资助下，共发表SCI论文8篇，申请国家发明专利2项。