可见光波段金属二维光子晶体的飞秒激光快速成型研究

As an important physical device to effectively control photonic signals, two-dimensional (2D) metallic photonic crystals at optical wavelength promise bright future applications in many areas such as nano-optics of surface plasmon polaritons, negative index materials and thermophotovoltaic systems. However, their rapid flexible development especially on large areas has been still a big challenge for current micro-manufacturing technologies. Facing this problem, we will present a new idea in this project that large-area (deep) submicron scaled 2D photonic crystals can be one-step fabricated on metallic targets, through using collinear time-delayed femtosecond laser pulses with different linear polarization directions. We will mainly investigate the critical roles of the time delay, the linear polarizations and the energy ratios among the laser pulses during the formation of 2D periodic structures, and discover the physical influence of the high vacuum or the low temperature environments on the uniform distribution of submicro-structures. A new approach of nonlinear adjusting the structural features will be found on the basis of ultrafast plasmon excitation on the transient nonequilibrium state of the materials. For the obtained metallic photonics crystals at optical wavelength, we will study their extraordinary optical properties and the potential functions. In addition, we will try to propose a theoretical frame to understand the physical mechanisms of such high efficient and flexible 2D fabrication processes under the irradiation of femtosecond laser pulses with proper time delays and different linearly polarizations. And then transient correlated effects among these multiple laser actions can be elucidated. It is believed that the carrying out of this project will open a new research field for femtosecond laser nano-writing with employing unusual properties of the materials.

可见光波段金属二维光子晶体作为有效操控光子信号的重要物理器件，在表面等离激元光学、负折射率材料和热光伏等领域有广阔应用前景，然而对其进行大面积快速灵活制备仍然是目前微加工领域面临的技术挑战。本研究项目拟提出采用共线传输的偏振异向飞秒激光延迟多脉冲经柱透镜聚焦在金属材料上，实现亚微米量级二维光子晶体一步成型和大面积制备的新方法。重点分析激光脉冲时间延迟、偏振特性和能量配比在二维周期结构形成过程中的关键作用，确立真空和低温加工环境对亚微米结构均匀构建的影响关系，掌握材料瞬态物理条件下超快表面波激发对二维结构非线性调控的新手段，探讨可见光波段金属二维光子晶体的奇异光学性能和功能化应用。建立理论描述框架，探索偏振异向和时间延迟的飞秒激光多脉冲对二维亚微米结构高效调控制备的内在机理，揭示它们在与金属作用过程中的瞬态关联效应，这对未来开辟利用材料非常态性能进行飞秒激光纳米光刻的新领域具有重要意义。

可见光波段金属二维光子晶体作为有效操控光子信号的重要物理器件，在表面等离激元光.学、负折射率材料和热光伏等领域有广阔应用前景，然而对其进行大面积快速灵活制备仍然是目前微加工领域面临的技术挑战。本研究项目提出采用时间延迟且偏振方向不同的飞秒激光经在材料表面实现亚微米量级光子晶体结构的高效率和高质量制备，并对其奇异光学性能和功能化应用给予了创新探索，取得的重要研究结果如下：（1）实验上成功建立了基于偏振方向和时间延迟可调的飞秒激光多脉冲在材料表面一步快速制备亚微米或纳米量级一维和二维周期阵列结构的加工装置。（2）掌握了飞秒激光对结构制作的单元形状、结构排列和加工效率的有效操控手段，实现了在高真空环境下材料表面深亚微米结构的均匀高质量产生。（3）分析了飞秒激光作用下二维光子晶体结构快速形成的基本原理，提出了材料表面瞬态折射率变化过程及对表面结构形成进行调控的物理模型。（4）首次在氧化石墨烯薄膜表面快速制备出了平行于入射激光偏振方向的高规整亚微米周期结构，并发现其具有化学还原和光电各向异性的新效应。（5）研究了金属纳米光栅对光波的传输特性，发现了级联光栅的透射谱在可见和红外波段分别出现三个透射率大于90%的峰值，深层揭示了其中表面等离激元波杂化耦合对光波操控的内在本质。这些研究结果对于未来拓展飞秒激光快速制备表面微纳结构及其实用化奠定了重要前期基础。