深亚波长约束的表面等离子体纳米激光器研究

本文提出了一种新颖的基于半导体纳米线/空气间隙/金属薄膜 复合结构的表面等离子体纳米激光器, 并给出了理论研究和仿真分析. 这种结构通过金属界面的表面等离子体模式与高增益介质纳米线波导模式耦合, 从而使场增强效应得到显著提高. 同时通过数值仿真研究, 得到该混合波导结构的模式特性和增益阈值随空气槽宽度、纳米线半径的变化规律, 表明它可以实现对输出光场的深亚波长约束, 同时保持低损耗传输和高场强限制能力. 通过最优化选择, 最终得到纳米等离子体激光器的最优结构尺寸. 关键词： 表面等离子体 混合等离子体波导 纳米激光器     

基于石墨烯加载的不对称纳米天线对的表面等离激元单向耦合器

本文设计并数值研究了一种石墨烯加载的不对称金属纳米天线对结构.利用石墨烯费米能级的动态调控特性,实现了电控表面等离激元的单向传输.类似于传统的三明治型纳米天线结构,设计的不对称金属纳米天线对结构可以等效为两个共振的磁偶极子,由于磁偶极子辐射电磁波的干涉,将导致单向传输效应.通过计算腔中的电场分布,发现石墨烯的调谐能力与石墨烯区域的电场强度成正比关系.以上现象都可以通过等效电路模型进行理论解释.此外,该结构具有小尺寸、高效率、宽带宽和易于光电集成等优点,在未来的光子集成与光电子学领域将具有重要的应用.     

金属-电介质约束的半导体微盘激光器

设计了一种以半导体材料InGaAsP作为核心结构的器件表面蒸镀二氧化硅膜层,在其上蒸镀金膜层,构成金属-电介质半导体微盘激光器结构,盘面的厚度为2 μm,盘面半径为6 μm,盘壁侧表面与底面的夹角为45°.使用有限元法对该结构器件的回音壁模式进行数值研究,利用所谓"偏微分方程的弱项形式"有效地抑制了许多局域不变性相关的"伪解".通过数值求解弱项型矢量亥姆霍兹方程,得到微盘激光器回音壁模式的横磁场分布,在此基础上讨论了其品质因数(Q值)、模体积、不同金属和电介质膜厚度对器件品质因数的影响、盘的半径和其品质因素的关系等相关量.理论计算表明,这种结构的器件较直接在介质表面蒸镀金属膜层结构的器件的品质因数高2～3倍.实验还获得了基阶和高阶的表面等离子体波模式,以及品质因数最大达到约5 400的光学-电介质基模.     

基于表面等离子体激元的纳米激光器设计

设计了一种基于纳米线/间隔层/金属层的纳米激光器结构.该结构中,金属界面的表面等离子体模式与高增益介质纳米线波导模式耦合,提高了场增强效应.采用有限元法,分析了该结构的模式特性和增益阈值随几何尺寸的变化规律.结果表明:该结构具有较低的传播损耗和较强的光场限制能力,有效传播损耗最小值仅为0.013 3,归一化模式面积最小值仅为0.007.该纳米激光器结构可为发展新一代高效纳米激光器件提供理论和技术支持.     

含色散特异材料三明治结构的量子悬浮效应

在金属板与电介质材料板基底间插入色散特异材料板形成三明治结构,并对其Casimir作用力进行了研究.基于Casimir-Lifshitz理论,通过麦克斯韦应力张量计算了真空涨落的辐射压,并对三明治结构利用电磁模式传输矩阵方法进行了数值计算分析.计算结果表明,原本两板结构中存在的Casimir吸引力,在插入特异材料板后的三明治结构中将转变为斥力,从而使轻薄的金属板产生量子悬浮效应。讨论了特异材料板的色散电磁响应特性以及电介质板基底的影响,结果表明特异材料磁等离子频率越大、磁共振频率越小以及电介质板基底的介电常数越小时,三明治结构中获得的斥力越大.此外,板间距增加到一定范围时,三明治结构中将出现Casimir平衡回复力.特异材料填充因子越小、三明治结构中层距和层厚越大时,三明治结构间的回复力会出现在较长距的位置.三明治结构中的量子悬浮效应与平衡回复力可保证微纳米机械系统稳定性,展现出基于真空辐射压的应用前景.     

金属-电介质约束的半导体微盘激光器

设计了一种以半导体材料InGaAsP作为核心结构的器件表面蒸镀二氧化硅膜层,在其上蒸镀金膜层,构成金属电介质半导体微盘激光器结构,盘面的厚度为2μm,盘面半径为6 μm ,盘壁侧表面与底面的夹角为45°.使用有限元法对该结构器件的回音壁模式进行数值研究.利用所谓“偏微分方程的弱项形式”有效地抑制了许多局域不变性相关的“伪解”.通过数值求解弱项型矢量亥姆霍兹方程,得到微盘激光器回音壁模式的横磁场分布,在此基础上讨论了其品质因数(Q值)、模体积、不同金属和电介质膜厚度对器件品质因数的影响、盘的半径和其品质因素的关系等相关量,理论计算表明,这种结构的器件较直接在介质表面蒸镀金属膜层结构的器件的品质因数高2～3倍,实验还获得了基阶和高阶的表面等离子体波模式,以及品质因数最大达到约5100的光学-电介质基模.     

基于锚形谐振腔的等离子体波导特性研究

基于表面等离子体激元在金属-介质-金属结构中优良的传输特性,设计了一种由直波导和锚形谐振腔组成的波导滤波器。仿真分析了波导滤波器传输特性和电场分布随结构参数和谐振腔内介质折射率变化规律。结果表明,该锚形谐振腔最佳结构时滤波器半峰全宽低至8 nm,品质因数高达121.9。利用共振波长与结构参数变化规律,设计了光通信波长窗口的窄带带阻滤波器。根据SPPs对谐振腔介质折射率敏感的特性,发现透射谱线随折射率变大而发生红移。本文提出的基于锚形谐振腔的等离子体MIM波导滤波器为设计特定波长的窄带带阻滤波器提供了新思路,也为基于谱线红移特性设计的介质折射率传感器提供了技术支持。     

基于金属包覆磁性波导结构的磁光Bragg器件特性分析

使用金属包覆磁性波导中的磁光耦合理论分析了静磁表面波与导波光在金属／电介质／钇铁石榴石／钆镓石榴石结构中的磁光共线作用，讨论了金属覆层和斜向场对磁光模式转换效率的影响。计算表明，金属包覆波导可以提高磁光作用，通过调节金属覆层与磁性薄膜间距得到了比空气／4a铁石榴石／钆镓石榴石的传统三明治波导情形高8．7dB的模式转换效率；而同时优化偏置磁场方向和金属包覆波导参数，模式转换效率可以进一步提高5．25dB。因此，金属包覆波导可以用于提高磁光Bragg器件性能，在微波和光信息处理等方面具有广阔的应用前蒂。     

介质光栅/金属薄膜与银立方体复合结构的SPs研究

理论设计了介质光栅/金属薄膜与银纳米立方体复合结构,通过有限元方法数值模拟计算了该结构中的超高电场增强因子.使用442nm波长的激光作为表面等离子体的激发光源,研究不同尺寸银纳米立方体的消光谱以及不同光栅周期和厚度的反射光谱,得到的该复合结构的最优参数为:光栅周期312nm,厚度90nm,银纳米立方体70nm.在最优参数条件下,数值模拟了复合结构中的电场增强分布,介质光栅/金属薄膜与银纳米立方体复合结构由于存在局域表面等离子体和传播表面等离子体的共振耦合,使得光栅脊与银纳米立方体下顶点接触处热点的电场增强因子高达1.53×106.该复合结构产生的超高电场增强因子,有望应用于表面增强拉曼散射的研究.     

基于多层膜结构的亚波长光栅研究

利用表面等离子体共振效应理论及金属-介质复合膜的特殊纳米光学效应对平面多层膜超分辨光刻技术进行了研究. 在曝光光源为365 nm的情况下,实现周期230 nm,线宽100 nm的超分辨光刻成像. 讨论了均匀金属-介质多层膜的结构参数选择,并通过数值仿真得到有效的光强度和对比度, 然后用等离子体纳米光刻进行试验验证,通过最优化选择,最终得到了亚波长结构多层膜的大区域范围超分辨成像.     

Magnetic plasmon mode resonance and power transmission in a nanosandwich waveguide

The magnetic plasmon (MP) modes in the metal-dielectric-metal nanosandwich structure are investigated nu-merically,and the principle of energy resonance in such a resonator is proposed.An equivalent inductance capacitance circuit analysis method is proposed and the results are in agreement with the numerical simulations.Based on the MP resonance in such a structure,a nanosandwich chain waveguide is designed.Gold and silver are chosen as the metal materials.The power transmission efficiency of the nanosandwich waveguide can be as high as 0.546 in a specific nanosandwich unit cell,even when the metal absorption loss is large,which is the perspective of the new waveguides and lasers based on MP modes.     

Mode analysis in microstrip resonators part II

In this contribution, the transmission line model for a printed circuit microstrip resonator is used to theoretically investigate the modes supported by simple structures. Computer analysis yields useful information on the harmonic response of resonators that is relevant to the design of printed antennas and harmonic generators.     

基于矩形谐振环的新型复合周期结构左手材料研究

通过实验及仿真研究了基于矩形谐振环的新型三角形和三矩形开口谐振环金属线复合周期结构左手材料.仿真研究了以金属铜三角谐振环和三矩形谐振环（SRRs）为基本单元的周期结构负磁导率材料,结果显示两种谐振环均能产生很好的谐振效果,即能产生负磁导率;设计、制作并实验和仿真研究了三角谐振环和三矩形谐振环金属线复合周期结构左手材料,实验结果分别在9.5—13.3GHz和9.8—12.5GHz出现良好的负折射效应,与仿真结果具有较好的一致性.该研究对新型周期结构左手材料的研究、设计和研制具有重要的科学意义和应用前景. 关键词： 左手材料 负折射 三角形谐振环 三矩形谐振环     

Experimental observation of left-handed behavior in an array of standard dielectric resonators

We demonstrate that by utilizing displacement currents in simple dielectric resonators instead of conduction currents in metallic split-ring resonators and by additionally exciting the proper modes, left-handed properties can be observed in an array of high dielectric resonators. Theoretical analysis and experimental measurements show that the modes, as well as the subwavelength resonance, play an important role in the origin of the left-handed properties. The proposed implementation of a left-handed metamaterial, based on a purely dielectric configuration, opens the possibility of realizing media at terahertz frequencies since scaling issues and losses, two major drawbacks of metal-based structures, are avoided.     

局域共振型声学超材料机理探讨

本文以二维固体薄板中的弹性波传播为例, 对基于共振子结构的声学超材料带隙机理进行了探讨, 证明在声学超材料中带隙形成既与共振子对波的散射相位有关, 也与波在共振体之间的几何传播相位有关. 通过调节散射相位和几何传播相位均能实现对色散关系的调控. 基于这一理解, 探究了弹性波超材料中的次波长缺陷态和负折射现象的实现条件.     

Possible Resonator Configurations for the Spherical Gravitational Wave Antenna

We solve algebraically the equations of motion for a spherical antenna coupled to an arbitrary number of small resonators, free to move radially, and investigate the conditions under which damping forces can be neglected in the system. We show that in order that the antenna's modes be decoupled a preferred distribution of the resonators on its surface should be used. We find that either 5, 6, 10 or 16 resonators can be used as long as they are conveniently positioned on the antenna's surface. We calculate and analyse the frequency shift and the signal-to-noise ratio of the coupled system for the various distributions studied.     

Relaxation- and decoherence-free subspaces in networks of weakly and strongly coupled resonators

We consider a network of interacting resonators and analyze the physical ingredients that enable the emergence of relaxation-free and decoherence-free subspaces. We investigate two different situations: (i) when the whole network interacts with a common reservoir and (ii) when each resonator, strongly coupled to each other, interacts with its own reservoir. Our main result is that both subspaces are generated when all the resonators couple with the same group of reservoir modes, thus building up a correlation (among these modes), which has the potential to shield particular network states against relaxation and/or decoherence.     

Double-cavity fiber structures as all optical timing extraction circuits for gigabit networks

In this paper we propose the application of double cavity fiber resonators as timing extraction circuits for gigabit networks. Spectral properties of double cavity fiber resonators, including the spectral enhancement achieved by means of the vemier effectare outlined. We investigate their suitability to obtain low cost all-fiber timing extraction circuits in broadband optical networks where single cavity structures previouslyproposed in the literature cannot be efficiently applied.     

Electrothermal automodulation in incipient ferroelectric whispering-gallery microwave resonators at 4.2 K

Threshold conditions for electrothermal automodulation instability in high-Q ferroelectric microwave cryogenic resonators operating in the two-mode regime are investigated. The dependence of the electrothermal automodulation frequency on the numbers of interacting modes for different combinations of thermal modes and surface electromagnetic whispering-gallery modes is presented. The threshold power exciting the electrothermal automodulation of the oscillation of the partial mode electromagnetic amplitudes is compared with the threshold power of strictional parametric excitation of acoustic oscillations in the resonator. It is shown that the electrothermal automodulation in the two-mode regime may take place at an excitation power from 10 to 120 μW depending on the combination of interacting thermal and electromagnetic surface modes. Calculated threshold powers are low, which makes it possible to apply the electrothermal automodulation for improving the sensitivity of resonance bolometers and distributed microwave antennas with basic elements built around nonlinear microwave resonators. In addition, the electrothermal automodulation could be applied in developing novel microwave metamaterials. Nonlinear microwave whispering-gallery cryogenic resonators can be used as elements increasing the sensitivity of EPR spectroscopy methods.