多重机制协同作用下金属微纳结构非线性辐射的增强与调控

Based on the cutting-edge progresses and applications of nonlinear plasmonics, this project will propose the enhancement and control of nonlinear emission from metallic micro-/nano-structures (MMNS) with the consideration of cooperative multiple mechanisms, such as the filed enhancement of the excitation wave, the field enhancement of nonlinear emission wave, and the "mode matching" between the two waves. Firstly, the conditions and mechanisms for high-efficiency second-harmonic generation (SHG), third-harmonic generation, and two-photon photoluminescence (TPPL) from gold nanorods and their hybrid nanostructures will be explored and clarified, with the help of versatile excitation schemes. Secondly, by carefully designing and fabricating two-dimensional metallic nano-hole arrays with multiple resonant wavelengths, the "double-resonance enhancement" of SHG will be studied. Polystyrene Kerr nonlinear polymer is further planned to be integrated with the metallic nano-hole arrays for the control of SHG. Thirdly, three-dimensional (3D) MMNS, such as hollow pyramid structures and conical structures and their modifications with micro-structures, will be designed and fabricated. With the utilization of vector beams and by engineering the polarization and wavefront of the excitation beams, 3D plasmonic focusing and the induced nonlinear emission from 3D MMNS will be studied. The well-designed 3D MMNS will be further fabricated on the top of a fiber tip, which will be explored for potential applications. The studies in this project could provide novel mechanisms for the enhancement and control of nonlinear emission from metallic micro-/nano-structures, as well as practical structures and methodologies for the applications of nonlinear micro-/nano-devices and technologies.

本项目结合非线性表面等离激元光学的发展和应用前沿，提出协同利用激发光的局域场增强、非线性信号光的局域场增强、以及激发光与信号光的"模式匹配"等多重物理机制，对多维金属微纳结构的非线性辐射进行增强和调控。采用多种泵浦方式，探索和明确二维金纳米棒结构中高效率二次谐波、三次谐波、双光子荧光产生的条件和调控机制。设计和制备具有多个共振模式的金属纳米孔阵列，研究纳米孔结构二次谐波的"双共振"增强，并采用聚苯乙烯克尔非线性材料对其进行调控。设计和制备表面修饰的空心金字塔及圆锥形三维金属微纳结构，结合矢量光束激发等手段，控制激发光的偏振和波前特性，研究结构对表面等离激元波的三维聚焦效应以及产生的非线性辐射增强效应。进一步研究将三维金属微纳结构制备到光纤端面，探索其与光纤的集成和应用。研究结果可望为金属微纳结构中非线性辐射的增强和调控提供新颖的机制，为非线性微纳光子器件和技术提供实用的物理结构和技术途径。

本项目结合表面等离激元结构中光与物质相互作用的发展和应用前沿，提出协同利用多重物理机制，对多维金属微纳结构的线性和非线性光学特性进行增强和调控。项目发展了有序金纳米棒结构阵列、金属纳米孔阵列衍生三维结构、纳米剪纸三维金属微纳结构等的新颖制备方法；设计和制备了空心金字塔及圆锥形三维金属微纳结构，研究了其对表面等离激元的三维聚焦效应；对结构的线性、非线性、手性等光学特性进行了深入研究，在多重物理机制协同作用下，获得了一种纳米剪纸三维金属微纳结构中手性相关的、增强的非线性辐射；将三维金属微纳结构制备到光纤端面，探索其与光纤的集成和应用。研究结果可望为多维金属微纳结构的制备及其在非线性微纳光子器件的应用方面提供重要的物理思路和技术途径。