【作者】 刘扬；

【导师】 徐红星；

【作者基本信息】 武汉大学 ， 凝聚态物理， 2019， 博士

【摘要】 表面等离激元是一种光激发下材料表面的自由电子集体振荡效应。自上个世纪六十年代发现表面等离激元现象以来相关的研究已经逐渐成熟。表面等离激元具有很多特殊的性质,可以将光局域在很小的空间尺度之内,形成很强的电磁场增强效应。表面等离激元也可以通过对入射光的频率选择效应来调制远场的光学响应。这些性质使表面等离激元成为了微纳光学中非常重要的组成部分。而近年来随着研究人员的深入探索,表面等离激元已不只是局限于微纳光学领域,而是和生物检测、化学分析、材料科学、信息技术等多领域交叉发展,成为了很多前沿科学技术的核心组成部分。本论文主要围绕大面积微纳结构产生的表面等离激元效应,结合实验结果及理论分析,研究探索了表面等离激元的近场增强效果及远场调制效应。具体来说,本论文的研究重点主要为以下两个方面。一、对于近场增强效应,设计并研究了一种双层金属光栅纳米结构,这种经过设计的双层金属光栅结构可以产生表面等离激元导致的电场增强,并同时产生光学腔模式这将使局域电磁场增强的范围扩大,而不止局限在金属表面。通过改变双层金属光栅的结构参数,以及仿真模拟计算分析,我们研究了不同电磁场增强模式的效果。这种并非局限在金属光栅表面的电场增强效应可以在提高原有的拉曼信号增强效果的同时也大大减少分子吸附在光栅表面的时间,实现了拉曼信号的即时探测。而这种利用微纳加工手段自上而下制备的纳米结构也具有很好的均一性稳定性以及可重复性,通过与微流系统的结合可以大大增加增强拉曼探测的实用性。此外也对金属表面吸附分子的荧光信号的增强效果进行了测量,为将来的生物检测打下来基础。二、对于远场调制效应,利用二氧化硅微球的表面等离激元效应对红外辐射效应进行了研究,并将二氧化硅微球混入表面多孔的有机高分子材料中,制备了可以在大气窗口范围高效进行红外辐射的材料,实现了较好的辐射制冷效果,白天与外界空气温度相比可以达到接近10度的制冷效果。同时测量了辐射制冷的功率及制冷效果,并对辐射制冷的实用化进行了探索。此外我们也对可以调制反射光波长的金属纳米结构进行了研究,并研究提出了两个可以批量化制作这些彩色纳米结构的加工方案。本文结合理论和实验研究了大面积微纳结构上表面等离激元的作用,主要针对其近场增强效果和远场调制效果进行了深入研究。并立足于自上而下的微纳加工手段,对大面积微纳结构的批量化制备进行了研究。本论文的工作加深了对表面等离激元的进一步理解,并为未来的基于表面等离激元的超结构的实用化可能性打下了基础。更多还原

【Abstract】 Surface plasmon is an effect of oscillation of free electron on metal surface under light.Related research has been studied since the discovery of surface plasmon phenomena in the 1960 s.Surface plasmons have many special properties such as a strong electromagnetic field enhancement effect within a small spatial scale.Surface plasmons can also modulate the optical response of the far field by the frequency selective effect on the incident light.These properties make surface plasmons a very important part of nano-optics.In recent years,with the exploration of researchers,surface plasmons have not only been limited to the field of nano-optics,but also have been cross-developed with many fields such as biological detection,chemical analysis,materials science,and information technology,surface plasmon become the important parts of many frontiers and the core component of science and technology.This thesis focuses on the surface plasmon effect generated by large-area micro/nano structures.Combined with experimental results and theoretical analysis,the near-field enhancement effect and farfield modulation effect of surface plasmons are studied.Specifically,the research of this paper is mainly focus on the following two aspects.Firstly,for near-field enhancement effects,we designed and studied a dual-layer metallic grating nanostructure.This designed dual-layer metallic grating structure can generate electric field enhancement caused by surface plasmons,and simultaneously generate optical cavity mode to enhance local electromagnetic field.The enhanced electric fields are not limited to metal surfaces.By changing the structural parameters of the dual-layer metallic gratings,by the simulation calculation and analysis,we studied the effects of different electromagnetic field enhancement modes.This electric field enhancement effect,which is not limited to the surface of the metal grating,can improve the original Raman signal enhancement effect and greatly reduce the time of molecular adsorption on the grating surface,realizing the instant detection of the Raman signal.The nanostructure prepared by the nano fabrication processing method which is from top to bottom also has good uniformity,stability and reproducibility,and the utility of the Raman detection can be greatly increased by the combination with the microfluidic system.In addition,we have also measured the enhancement of the fluorescence signal of the adsorbed molecules on the metal surface,laying the foundation for future studies of biological detection.Secondly,for far-field modulation effects,we studied the effect of infrared radiation by the surface plasmon effect of silica microspheres,and mixed the silica microspheres into the porous organic polymer material.This material can efficiently perform the radiative effect in the atmospheric window.The infrared radiation material achieves better radiation cooling effect,and can achieve a cooling effect close to 10 degrees compared with the outside air temperature during the daytime.At the same time,we measured the power and cooling effect of radiant cooling,and explored the practical application of radiant cooling.In addition,we have also studied metal nanostructures that can modulate the wavelength of reflected light,and have proposed two processing schemes that can mass produce these colored nanostructures.In this paper,the effects of surface plasmon on large-area micro/nano structures are studied in combination with theory and experiments.The near-field enhancement effects and far-field modulation effects are studied in depth.Based on the top-down nanofabrication processing method,the batch preparation of large-area micro/nano structure was studied.The work of this paper has deepened the understanding of surface plasmons and laid the foundation for the future practical application of surface plasmon-based superstructures.更多还原