【作者】 刘玉洁；

【导师】 杨宏伟；

【作者基本信息】 南京农业大学 ， 生物物理学， 2016， 硕士

【摘要】 石墨烯的出现,有望从构造材料到用于电子器件的功能性材料等众多领域,引发材料革命。石墨烯具有零带隙、低电导率、常温下的高电子迁移率、量子霍尔效应、独特的光吸收和非线性光学等优良特性。此外,石墨烯也具有金属特性,单层石墨烯的厚度仅有0.34nm,可将其看成是一种非常薄的网状纳米金属结构。并且石墨烯的宽波段调节性、制作工艺简便和与现有的半导体兼容等优良特性也引起了学者的关注。石墨烯在复合材料、光电器件和生物医药等领域有着很好的应用前景。对石墨烯复合材料的研究主要集中在石墨烯聚合物材料和石墨烯基无机复合材料,近年来的研究进展表明石墨烯-金属基复合材料和石墨烯-等离子体复合材料也受到人们的关注。本文采用传输矩阵法对掺杂石墨烯缺陷的光子晶体进行仿真,并对其进行理论分析研究。通过对一维掺杂石墨烯缺陷的光子晶体的仿真,研究发现其双频吸光特性与光子晶体周期数、石墨烯层数、间隔层介质厚度、入射角度等密切相关。研究结果表明,增加石墨烯层数时,对波长为699nm左右处和1000nm左右处的光吸收作用增强;缺陷层介质厚度减小引起吸收率的增加和吸收峰向着波长减小的方向移动;在TE模式下,入射角的改变使得光子晶体吸收峰有规律地变化。该研究结果为一维掺杂石墨烯缺陷的光子晶体双频吸收器的设计和应用提供了理论依据。本文构建的光子晶体厚度较小,在一定程度上,不仅节约了原材料的使用,使得光子晶体的制作更加简单方便,而且能将其应用于多种吸收器件。研究表明介质厚度的改变,也将引起吸收峰个数及位置的改变,或将出现单频、双频或多频吸收,为光子晶体吸波器件的设计提供理论依据。目前,多数吸收器件都是互易的,即吸收材料的吸收率与入射方向无关。近年来旋光材料的磁光效应(强磁场对光和介质相互作用的影响)越来越受到人们的关注,非互易传输器件的研究逐步进入热潮。磁光材料的介电常数或磁导率具有非对角元,它破坏了时间反演对称,但要实现非互易传播还必须同时破坏空间的反演对称。本文在光子晶体中加入旋光介质,依次比较时间反演对称和空间反演对称对结构非互易传输的影响,寻求最佳构型。研究表明旋光介质参数的改变,对构型的吸收率和非互易传输特性有一定的影响,吸收峰的峰值随着介质参数的增大向波长减小的方向移动,且伴有吸收率的减小。旋光介质的加入,实现了吸收器的非互易传输,合理利用结构的两面,使其具有不同的吸光特性。更多还原

【Abstract】 At present,the majority of current designs focus on building an elaborate metallic pattern on a thin dielectric spacer film,which attach to a thick metal layer.It is worth noting that most reported absorber designs contain miniature and elaborate structural features,and then it is setting manufacturing obstacles for the practical applications of super absorbers.The emergence of the graphene,is considered to be a promising material for realization of ultra-fast optoelectronic devices,and may lead to materials revolution in other fimctional materials and many other fields.In recent years,the research and application of graphene covers a wide range of fields,and the research and application of graphene covers a wide range of fields.Due to the excellent nonlinear properties,absorption properties of metals and wide band adjustment,graphene is used to design an absorbing device instead of metal layer.The introduction of graphene i5 devoted to study the variation of the absorption characteristics,and design one-dimensional photonic crystal structure with dual band absorption.Graphene layers have a significant effect on the absorption.Currently,the study of dual-band and multi-band absorption is lesser.In this paper,dual-band absorption can be realized by engineering an asymmetric one-dimensional photonic crystals(1DPC)with a defect based on graphene.The dual-band absorption characteristics of one-dimensional photonic crystals with graphene-based defect were theoretically analyzed and numerically simulated using the transfer matrix method(TMM).The dependence of dual-band absorption characteristics on period number M of the structure behind the graphene layer,graphene layers,dielectric thickness of defect layer,and the incident angle are obtained.Simulation results show that the absorptions with the lights with wavelength 699nm and 1000nm approximately are enhanced with the increasing of the layers of graphene.The absorption peaks increase with the decreasing of the dielectric thickness of defect layer and move toward the shorter wavelength.In the TE mode,the absorption peak can be regularly tuned by varying the incident angle.In this paper,the 1DPC engineered saves raw material to a eertain degree,and the preparation process i5 simpler due to the smaller total thiekness and is convenient for application in a variety of absorbers.In addition,the number and position of absorption peaks can be adjusted by changing the dielectric thickness and defective media.This paper provides the theoretical basis for the study of graphene absorbers,and the designing concept for its application.Most absorption devices are reciprocal,at present.The absorption rate of the absorption material is independent to the incident direction.Along with the research of optically active materials gradually coming,the magneto-optical effect(the effect on the interaction of magnetic field on light and medium)is applied to nonreciprocal transmission device.The dielectric constant or permeability of magnetooptical materials is non-diagonal element,which destroys the time reversal symmetry.In order to achieve the nonreciprocal transmission,the inversion symmetry of the space must be destroyed at the same time.This paper adds the magneto-optical material into the multilayer composite membrane,and the effects of the time reversal symmetry and the spatial inversion symmetry on the nonreciprocal transmission of the structure are compared,and then at last finds the best structure.By changing the parameters of the magneto-optical material,the effect on the absorption and the nonreciprocal transmission of the structure are studied.The addition of the magneto-optical material,achieve the goal of the nonreciprocal transmission,and the two direction of the structure will be both used rationally.更多还原