SGER: Designing Active Nanostructures from Passive Metallic Films

技术：本提案描述了用纳米级孔阵列穿孔的金属薄膜的基础研究。PI计划研究如何用一种简单但革命性的方法在贵金属薄膜上制造结构，从而将扁平的钝化薄膜转变为活性纳米结构。具体来说，PI建议研究贵金属薄膜中这些小孔的大小、形状和排列如何在操纵光方面发挥积极作用。为了表征这些纳米结构薄膜的特性，PI计划测量相同薄膜的局部和集体光学行为。因此，可以对孔金属薄膜进行完整的近场和远场研究，以描绘表面等离子激元的激发、传播和干涉。该项目集成了一种新方法，利用复杂的工具在薄金属薄膜上制造纳米孔阵列，以表征其光学特性。这种组合使PI能够解决表面等离子体如何通过孔阵列介导增强传输的问题，因为PI可以将表面等离子体的近场图像与其远场光谱相关联。这种对同一金属薄膜的局部和集体研究将使PI能够区分表面等离子激元极化子和局部表面等离子激元激发、传播和干涉。以前对亚波长空穴阵列的研究只关注它们的远场特性，而没有关注潜在的近场现象，这对于提出的增强光传输的机制至关重要。我们将探索纳米孔金属膜作为活性纳米结构的三种相互关联但不同的方式。这些策略包括：(i)在具有宽间距孔阵列的薄膜上操纵SPs成驻波模式，（ii）通过间距紧密的孔阵列增强和准直光传输，以及（iii）通过改变偏振来控制通过薄膜传播的光的颜色和局部模式。非技术：研究将做出重要的贡献，不仅了解光是如何通过孔传输的，而且还将使人们能够在金属薄膜中设计不同的结构，这些结构具有展示其他有趣和意想不到的光学特性的潜力。这项工作可以深入了解这个存在了十年之久的问题，并推动除了表面等离子体外，空穴阵列中其他有趣的现象，如Wood异常、衍射和波导模式。外展活动将主要集中于将研究活动整合到课堂中，并为7-16年级的学生开发纳米科学和光子学领域的内容。具体来说，由NSFNUE项目赞助的一门面向二年级学生的新的研究型课程将于2006年冬季和春季开设。此外，PI还为美国国家科学基金会纳米学与教中心（NCLT）教师的教育和专业发展做出了贡献。

TECHNICAL: This proposal describes fundamental studies of thin metallic films perforated with arrays of nanoscale holes. PI plans to investigate how a simple but revolutionary procedure to create structure on thin noble metal films can transform flat passive films into active nanostructures. Specifically, PI proposes to investigate how the size, shape, and arrangement of these small holes in noble metal films can play an active role in manipulating light. To characterize the properties of these nanostructured films, PI plans to measure the local and collective optical behavior of the same films. Therefore, complete near-field and far-field studies of metallic films of holes can be carried out to delineate among surface plasmon excitation, propagation and interference. The project integrates a new approach to fabricate nanohole arrays in thin metal films with sophisticated tools to characterize their optical properties. This combination allows PI to address the question of how surface plasmons can mediate enhanced transmission through hole arrays because PI can then correlate the near-field images of surface plasmons with their far-field spectra. Such local and collective studies on the same metallic films will enable PI to distinguish among surface plasmon polariton and localized surface plasmon excitation, propagation, and interference. Previous studies of subwavelength hole arrays have focused solely on their far-field properties and not on the underlying near-field phenomena, which is critical in the proposed mechanism for enhanced optical transmission. PI we will explore three inter-related but distinct ways that nanohole metallic films can function as active nanostructures. These strategies include: (i) manipulating SPs into standing wave patterns on films with arrays of widely spaced holes, (ii) enhancing and collimating the light transmission through arrays of closely spaced holes, and (iii) controlling the color and localized modes of light propagating through the films by changing the polarization. NON-TECHNICAL: Research will allow important contributions to be made not only for understanding how light is transmitted through the holes but will also enable one to design different structures in the metal films with potential to exhibit other interesting and unexpected optical properties. This work can provide insight into this decade-old problem as well as push forward other interesting phenomena in hole arrays besides surface plasmons, such as Wood's anomalies, diffraction, and waveguide modes. Outreach activities will concentrate primarily on the integration of research activities into the classroom and the development of content for 7-16 grade levels in the area of nanoscience and photonics. Specifically, a new research-based course for sophomores, sponsored by the NSFNUE program is being offered in Winter and Spring 2006. In addition, PI is contributing to the education and professional development of teachers in the NSF-Nanoscale Center for Learning and Teaching (NCLT).