基于金属纳米颗粒－绝缘体复合材料的平板光子晶体的制备、带隙调制及机理研究

Photonic crystal (PC) presents many fire-new properties due to the existence of photonic band gap, and can be used in various fields such as filter, optical fiber, optical switch, sensing, imaging, photovoltaic cell, laser, etc. Constructing the required periodic structure in the metal/insulator nanocomposite synthesized to get a zero or negative effective permittivity is an effective way to fabricate PC with a large band gap and/or to tune the band gap of PC in a wide range. In this project, metal ion implantation at a high fluence and electron beam lithography will be combined to fabricate wide-band-gap PC slabs based on the formation of metal nanoparticles-insulator composites with special dielectric properties. The fabricated PC slabs are designed to have lattice constant of hundred nanometers, and therefore their band gaps are located in visible and/or near infrared region. Moreover, several methods, such as pre-implantation and post-irradiation of heavy ions, will be used to modify the metal nanoparticles embedded in composites. As a result, the photonic band gaps can be regulated in a wide range. Over the course of study, various techniques will be employed to characterize the fabricated PC slabs and the corresponding composites, mainly investigating how the photonic band gap is influenced by the dielectric constant of insulator, the layer number and lattice constant of PC slab as well as the component, density, size and spatial distribution of the embedded metal nanoparticles. On these bases, the micro-mechanism about the formation and modulation of photonic band gap will be revealed. The obtained results can provide experimental and theoretical bases for the fabrication of wide-band-gap PCs together with their applications in the approaching photonic industry.

光子晶体因存在光子带隙而表现出许多崭新的性质，在滤波器、光纤、光学开关、传感、成像、光电池、激光等领域有着广阔的应用前景。研制有效介电常数为零或负的金属/绝缘体纳米复合材料并以之为基础构建周期性结构是制备宽带隙光子晶体并实现其带隙调制的有效途径。本项目拟将高剂量的金属离子注入与电子束光刻技术相结合，通过合成具有独特介电性质的金属纳米颗粒－绝缘体复合材料，进而获得晶格常数为几百纳米的宽带隙平板光子晶体，同时还将采用重离子预注入和后续辐照等方法，通过对金属纳米颗粒的调控，实现光子带隙大范围的调制。研究中将借助多种分析手段对所制备的平板光子晶体及相应的复合材料进行表征，考察光子带隙随绝缘体的介电常数、平板光子晶体的层数和晶格常数以及金属纳米颗粒的成份、密度、尺寸和空间分布等的演变规律，揭示光子带隙形成及调制的微观机制。该研究可为宽带隙光子晶体的制备及其在光子产业中的应用提供实验和理论依据。

光子晶体因存在光子带隙而表现出许多崭新的性质，在滤波器、光纤、光学开关、传感、成像、光电池、激光等领域有着广阔的应用前景。金属离子注入绝缘体材料合成的金属／绝缘体纳米复合材料可以改变材料的有效介电常数，这为以此类纳米复合材料为基础构建宽禁带光子晶体并调制其带隙提供了途径。本项目首先基于金属离子(Ti、Zn、Cu、Ag、Au等)单注入或顺次注入到典型的绝缘体材料(SiO2、YAG、LiNbO3等)合成了一系列金属或氧化物／绝缘体纳米复合材料，在揭示其结构、光特性等的基础上，重点以所制备的各类金属／SiO2纳米复合材料为主体，结合电子束光刻、反应离子束刻蚀及磁控溅射等技术成功构建了两类平板光子晶体，即由周期性网状结构组成的单层平板光子晶体和由周期性多层结构组成的多层平板光子晶体，详细地研究了它们的光学特性及变化规律。通过研究，获得了以下创新性成果：(1)发现所构建的M(Ag、Cu和Au)/SiO2纳米复合材料二维网状周期性结构能将特定波长的光束耦合进平面波导，并从实验和理论上揭示了该类结构的光耦合波长的范围和效率对金属纳米颗粒的成分、尺寸、空间分布及体积分数等的依赖规律；(2)在M(Ag、Cu和Au)/SiO2纳米复合材料二维网状周期性结构结构上观测到了衍射扭曲现象，并揭示了倾斜入射条件下导波偏转所遵循的规律以及其等离子体行为与间隙衍射和局域化等离子体共振吸收之间的关系；(3) 在含金属／绝体体纳米复合材料的多层周期性结构上，观测到了反射率急增效应，且反射率随结构层数的增加呈现线性变化关系，在仅4层结构的样品上得到了近70%的反射率；研究同时还揭示了反射率变化来源于金属纳米颗粒尺寸和体积分数的协同作用；(4) 发现了利用低能高剂量的贵金属离子注入SiO2基底合成的纳米复合材料能够作为高稳定性的局域化表面等离子体共振传感器。以上研究成果为构建基于金属／绝缘体纳米复合材料的宽带隙光子晶体及全反射布拉格反射镜的制备及光特性调控提供了实验和理论基础。项目研究完成了预期的研究目标，发表标注的SCI论文12篇，申请国内发明专利1项，培养毕业博士生2名，硕士生4名。