【作者】 朱鹏；

【导师】 金鹏； 郭凌杰；

【作者基本信息】 哈尔滨工业大学 ， 仪器科学与技术， 2013， 博士

【摘要】 金属纳米结构具有众多特殊的电磁特性，在光学传感、生物检测、光伏器件以及表面增强拉曼光谱等领域具有广泛的应用前景。作为构建新一代纳米光学器件的重要组成部分，金属纳米结构是克服光学衍射极限，实现高性能、微型化和高效率的集成光学系统的关键元件，其优异的性能源于金属纳米结构中表面等离子体的光场调制作用。利用表面等离子体的高度局域性和亚波长特性，可以在纳米尺度实现对光场的调节与操纵，从而制作出更小、更快、更轻的光学器件，并能实现一些传统器件难以实现的功能。近年来，随着微纳米加工和表征技术的快速发展，基于金属纳米结构的等离子体光学器件的研究取得了巨大的进展，涌现出许多具有特殊的光场调制能力的新型器件。然而现阶段人们对金属纳米结构光学器件及其应用的研究总体上还不完善，现已提出的大部分金属纳米结构器件制作工艺复杂，缺乏高效率的低成本批量加工方法，这些都将极大制约金属纳米结构器件的产业化生产和在实际领域的大规模应用。本课题基于金属纳米结构中表面等离子体的光场调制方法研究围绕金属/电介质多层膜纳米结构的近场和远场区域的光学性质，从光场调制的角度选取深度亚波长干涉光刻、超薄型等离子体光吸收器件和光学漏斗效应等应用前景广泛的领域展开深入系统的研究，对促进我国纳米光子学器件和相关纳米技术的发展起到积极的推动作用。本论文的主要研究内容和创新性工作包括：1.研究多层膜金属纳米结构近场光学调制能力。系统的讨论等效介质理论模型在分析有限层金属/电介质多层膜结构时的局限性，为等离子体干涉光刻器件的设计优化和实际应用提供理论上的指导；进一步提出从波导耦合的角度分析表面等离子体在金属/电介质多层膜结构中的传播特性，在此基础上通过有限元数值仿真的方法提出并验证一种亚波长等离子干涉光刻方法，显著提高干涉图案的对比度与图案深度，降低所需光栅掩模版的加工难度。2.设计并制作一种基于金属/电介质/金属(MIM)波导结构的新型可见光波段的宽波段光吸收器。从MIM结构特殊的色散曲线和等离子体共振分析其原理，并从实验角度去验证该特性。所设计的结构具有平坦的吸收光谱和高效的光谱吸收效率，吸收光谱带宽可拓展至整个可见光波段，在有机发光二极管和薄膜太阳能电池等领域有重要的潜在应用价值。3.通过理论和实验阐述一种金属/电介质多层膜结构中的光学漏斗效应。利用金属/电介质多层膜中亚波长宽度的垂直沟槽，可将外部区域中的光场汇集到远小于入射光波衍射极限的区域中，在反射光谱的共振波长处可以得到反射率几乎为零的波谷。此外拓展了单层金属膜中光学漏斗现象的应用范围，研究不同深度的沟槽对反射光谱宽度的影响。上述现象和结论在红外传感和探测领域具有重要的应用前景。更多还原

【Abstract】 Metallic structures have plenty of special electromagnetic properties andpromising potential applications in optical sensing, biomedical detection, photovoltaicdevices and surface-enhanced Raman scattering. They are also the important parts ofnano-photonic devices for the next generation, which are the key components toovercome optical diffraction limit and construct intergrated optical systems with highperformance and miniaturization. These functions are related to the surface plasmonswhich are excited at the metal surface. Utilizing the properites of high localization andenhancement of SPPs, we can realize controlling and modulation of light atnano-scales. So some convential optical devices may be replaced by new smallerfunctional nano-devices and even achieve some special capabilities which can not bedone by convential devices. In revent years, there are significant progresses in theresearch of plasmonic optical devices based on metallic nanostructures as thedevelopment of nano-fabrication and measurment technologies. However, theresearch on light modulation with metallic nanostructures is still limited in the lab.Plenty of plasmonic related phenomena require deep understandings and clearexplanations, more new concepts and effects are worthy to be exploited. Beseds, thefabrication processes of many proposed nanostructure based devices are verycomplicated and there is no efficient low cost baich fabrication method, which greatlylimits the applications of nanostructure devices in the industrial areas.The project "Research on theories and applications of light field modulationbased on SPPs in metallic nanostructures" mainly focuses on the optical properties ofmetal/dielectric multialyer nanostructures and take systematic research on twopromising areas: plasmonic interference lithography and light absorption from thepoint of view of near-field and far-field of the structures. The results play a positiverole in promoting the development of nano-optical devices and relatednano-technologies in our country.The main research contents and innovative works include:1. We discussed the limitations of effective media theory (EMT) on analyse ofmetal/dielectric structure finited layers from the prespective of SPP propagationproperty, reflection sprctrum and distribution characteristics of interference patterns.These results based EMT are compared with rigirous electromagnetic analysis methodand provide useful guidelines for the optimization andpractical application ofplasmonic interference devices. The propagation properties of SPP in metal/dielectricmultilayer film structures are analysed from the ponit of view of waveguidecoupling and the expression of beam spreading angle and conditions of uniforminterference patterns are obtained. A subwavelength plasmonic interferencelithography method is proposed and demonstrtated by numerical simulations based on above analyses, which can significantly increase the contrast and field depth of theinterference patterns and decrease the fabrication difficulty of grating mask. Thefeature size of the uniform periodic patterns is1/8of incident wavelength, the contrastis as high as0.8and the depth is80nm by introducing the SPP coupling from thebottom of photoreisit.2. A broadband plasmonic absorber in visible range based onmetal/dielectric/metal structure is proposed and experimentally demonstrated. Twokinds of structures are designed and fabricated. Structure-I with single layer ofgratings has a theoretic absorption of nearly100%(measured averaged value of80%)from a broadband range of400nm t0600nm for TM polarized light and thestructure-II with double layer gratings can further extend the absorption spectrum tothe whole visible range. The mechanism of broadband absorption is analysed by boththeoretic calculations and numerical simulations and the special vertical dispertion ofthe MIM structure is found. The angle response and robustness of the structure arealso discussed. Compared to previously reported structures, our designed structure hasmore flat absorption spectrum and high absorption ratio. Besides, its structure issimple and stable, suitiable for the large area fabrication with roll to roll nanoimprinttechnology.3. A light funneling effect in metal/dielectric mulitlayer films is proposed anddemonstrated by simulation and experiemtal method. Incident light at the resonantwavelength can be completely funneled into dielectric layers through a narrow groovethat only covers12.5%of the surface area within one period and absorbed by aresonant cavity composed of metal/dielectric multilayer films. A narrower resonantdip is observed than that produced by bulk metals with the same thickness andgrooves. The mechanism and influencing factors of the reflection spectrum, includinggroove widths, layer numbers and profile of groove’s side wall are comprehensivelyanalyzed. Coupling between the adjacent grooves with different depths are alsodiscussed. Besides, we expand the application scope of light funneling effect in singlelayer metal film by studying the reflction spectrum of strucuture with two grooveswith different depths. Our study can be applied in the applications of biologicalsensing and infrared detectors.更多还原