偏振不敏感的表面等离激元三维聚焦研究获进展

正表面等离激元(surfaceplasmons)是一种局域在金属和电介质界面处的电磁场模式,能够突破光学衍射极限,将携带的光学信息和能量局域在亚波长尺度。在高端纳米光学应用领域,如高分辨近场光学成像、针尖增强拉曼光谱,光学集成器件、纳米光     

太赫兹波段表面等离子光子学研究进展

表面等离子光子学是研究金属、 半导体纳米结构材料独特的光学特性, 是目前光子学中最有吸引力、 发展最快的领域之一. 伴随着微/纳制造技术与计算机模拟技术的进步, 表面等离子光子学在可见光、 红外、 太赫兹以及微波频域得到了广泛研究, 在高灵敏生化传感、 亚波长光波导、 近场光学显微、 纳米光刻等领域有潜在的应用价值. 特别是人工超材料的发展, 为自然界长期缺乏响应太赫兹波的材料和器件奠定了基础, 从而也促进了太赫兹波段表面等离子光子学的研究. 本文从太赫兹表面等离子波的激发、 传导、 最新应用及未来发展趋势等几个方面进行了回顾和讨论, 将最新研究成果展示给读者.     

介质填充浅槽周期结构表面上的太赫兹表面等离子体激元

通过在金属表面刻成浅的垂直凹槽,并在槽内填充不同的介质,对金属表面浅槽周期结构上传播的表面等离子体激元的色散特性与填充介质的关系进行了研究.研究表明通过在周期凹槽内填充介质可以有效降低人工表面等离子体激元的渐近频率,并增强金属表面对电磁场的约束.分析了太赫兹波段金属的吸收损耗对人工表面等离子体激元特性的影响,结果显示基于填充介质的浅槽周期表面结构可以获得长距离传输以及场的亚波长约束.通过对波传输的数值仿真,验证了该表面结构在太赫兹波段良好的导波能力.这种表面结构对太赫兹波段新型集成导波器件的设计具有参考价值.     

介质填充浅槽周期结构表面上的太赫兹表面等离子体激元

通过在金属表面刻成浅的垂直凹槽,并在槽内填充不同的介质,对金属表面浅槽周期结构上传播的表面等离子体激元的色散特性与填充介质的关系进行了研究.研究表明通过在周期凹槽内填充介质可以有效降低人工表面等离子体激元的渐近频率,并增强金属表面对电磁场的约束.分析了太赫兹波段金属的吸收损耗对人工表面等离子体激元特性的影响,结果显示基于填充介质的浅槽周期表面结构可以获得长距离传输以及场的亚波长约束.通过对波传输的数值仿真,验证了该表面结构在太赫兹波段良好的导波能力.这种表面结构对太赫兹波段新型集成导波器件的设计具有参考价值.     

范德华尔斯材料在转角光学中的研究进展

极化激元是光与不同极化子相互作用形成的半光半物质的准粒子,可用于亚波长尺度的光场调控,在光学成像、非线性效应增强及新型超构材料设计等领域扮演着举足重轻的角色。近年来,随着人们对转角范德华尔斯材料体系的制备工艺和物性研究的不断深入,其中许多新奇的极化激元现象也被揭示。本文综述了近年来转角范德华尔斯材料在光学领域的研究进展,包含转角石墨烯体系中的等离极化激元,转角二维过渡金属硫化物中的激子极化激元与六方氮化硼(h-BN)与α-MoO_3体系中的声子极化激元等。最后展望转角二维范德华尔斯材料中的极化激元在纳米尺度下光与物质相互作用的有效控制方面所展现的巨大潜力。     

叠层/转角二维原子晶体结构与极化激元的近场光学表征

极化激元是一种光与物质发生强相互作用形成的准粒子,可以极大地压缩光波长,提供一种突破衍射极限的光调制方式,为纳米光子学、非线性光学、量子光学等相关学科的发展提供了重要支持.范德瓦耳斯二维原子晶体是研究极化激元的理想平台,通过叠层、转角可以为极化激元的调控提供额外的自由度,从而展示出新颖的光学结构和极化激元特性.本文以近场光学为主要研究方法,对近几年出现的叠层及转角二维原子晶体的各种光学结构及极化激元进行综述.综述内容包括叠层石墨烯的畴结构、转角二维原子晶体的莫尔超晶格结构、转角二维拓扑极化激元、转角石墨烯手性等离激元等.最后,对叠层/转角二维原子晶体及其极化激元的未来发展进行展望.     

一种石墨烯波导褶皱激发表面等离子体激元的设计

设计了褶皱石墨烯波导结构激发表面等离子体激元,通过设计周期阵列结构实现了表面等离子体激元传播损耗的补偿.理论分析了周期阵列结构的表面等离子体激元传播模型和补偿损耗的方式,结果表明褶皱衍射激发表面等离子体激元波导不仅能够激发表面等离子体激元,还能利用表面等离子体激元波矢关系实现器件参数控制,周期阵列增益全程补偿损耗的方式可以显著增加表面等离子体激元的传播距离.数值分析结果进一步表明:该结构具备了保持亚波长尺寸的强局域化优势;周期阵列增益全程补偿可以显著提高纳米腔中的电场强度,降低传输损耗;波导结构的粒子反转水平较高,自发辐射噪声的扰动较低.设计的石墨烯波导器件可以为微纳光学集成、光子传感和测量等领域提供理想的亚波长光子器件.     

一种石墨烯波导褶皱激发表面等离子体激元的设计（英文）

设计了褶皱石墨烯波导结构激发表面等离子体激元,通过设计周期阵列结构实现了表面等离子体激元传播损耗的补偿.理论分析了周期阵列结构的表面等离子体激元传播模型和补偿损耗的方式,结果表明褶皱衍射激发表面等离子体激元波导不仅能够激发表面等离子体激元,还能利用表面等离子体激元波矢关系实现器件参数控制,周期阵列增益全程补偿损耗的方式可以显著增加表面等离子体激元的传播距离.数值分析结果进一步表明:该结构具备了保持亚波长尺寸的强局域化优势;周期阵列增益全程补偿可以显著提高纳米腔中的电场强度,降低传输损耗;波导结构的粒子反转水平较高,自发辐射噪声的扰动较低.设计的石墨烯波导器件可以为微纳光学集成、光子传感和测量等领域提供理想的亚波长光子器件.     

二维电子气等离激元太赫兹波器件

固态等离激元太赫兹波器件正成为微波毫米波电子器件技术和半导体激光器技术向太赫兹波段发展和融合的重要方向之一。本综述介绍AlGaN/GaN异质结高浓度和高迁移率二维电子气中的等离激元调控、激发及其在太赫兹波探测器、调制器和光源中应用的近期研究进展。通过光栅和太赫兹天线实现自由空间太赫兹波与二维电子气等离激元的耦合,通过太赫兹法布里-珀罗谐振腔进一步调制太赫兹波模式,增强太赫兹波与等离激元的耦合强度。在光栅-谐振腔耦合的二维电子气中验证了场效应栅控的等离激元色散关系,实现了等离激元模式与太赫兹波腔模强耦合产生的等离极化激元模式,演示了太赫兹波的调制和发射。在太赫兹天线耦合二维电子气中实现了等离激元共振与非共振的太赫兹波探测,建立了太赫兹场效应混频探测的物理模型,指导了室温高灵敏度自混频探测器的设计与优化。研究表明,基于非共振等离激元激发可发展形成室温高速高灵敏度的太赫兹探测器及其焦平面阵列技术。然而,固态等离激元的高损耗特性仍是制约基于等离激元共振的高效太赫兹光源和调制器的主要瓶颈。未来的研究重点将围绕高品质因子等离激元谐振腔的构筑,包括固态等离激元物理、等离激元谐振腔边界的调控、新型室温高迁移率二维电子材料的运用和高品质太赫兹谐振腔与等离激元器件的集成等。     

石墨烯与太赫兹科学

石墨烯(Graphene)是材料科学和物理科学领域一颗冉冉升起的新星.作为一种具有优异晶体品质和电子性质的二维材料,石墨烯表现出独特的电子输运、光学耦合、电磁学和其他新奇的性质.例如,石墨烯的禁带宽度和有效质量为零,其电子和空穴的运动方式与相对论性粒子相同,另外,石墨烯拥有已知材料中最高的迁移率,且其迁移率基本与温度无关,石墨烯具有众多的新颖物理现象和应用潜能,其中在太赫兹科学上的应用前景尤其广阔.石墨烯的等离子振荡、可外部控制的导电率及可人为调谐的禁带宽度都与太赫兹科学息息相关.文章重点地介绍了石墨烯的基本性质和最新研究进展,并展望了石墨烯在太赫兹科学上的应用前景,包括石墨烯的太赫兹特性研究及石墨烯太赫兹器件.     

Nonlinear spoof surface plasmon polariton phenomena based on conductor metamaterials

We present nonlinear phenomena produced from spoof surface plasmon polariton (SSPP) modes. Below the THz spectrum, artificially textured conducting metastructures on a subwavelength scale generate surface-bound modes and are called SSPP modes, similar to surface plasmon polariton (SPP) modes in the visible spectrum. Even though nonlinear effects in the THz domain are negligible, subwavelength metallic gap structures are ideal candidates to realize nonlinear behavior in the THz domain because of slow light propagation, strong electromagnetic confinement, and a high quality factor Q. In particular, when SSPP structures are combined with Kerr nonlinear materials, nonlinear-bistable curves can be observed below the THz spectrum.     

Suppression of radiative losses of surface polaritons on nanostructured thin metal films

The strong electromagnetic coupling between surface plasmon polariton modes on opposite interfaces of a finite thickness periodically nanostructured metal film has been studied. Surface polariton dispersion and associated electromagnetic field distributions have been analyzed. It was shown that at a frequency that corresponds to the crossing of film Bloch modes of different symmetries, the radiative losses of surface polaritons that are related to the polaritons' coupling to light during propagation on the structured surface are suppressed.     

Ultrastrong light-matter coupling regime with polariton dots

The regime of ultrastrong light-matter interaction has been investigated theoretically and experimentally, using zero-dimensional electromagnetic resonators coupled with an electronic transition between two confined states of a semiconductor quantum well. We have measured a splitting between the coupled modes that amounts to 48% of the energy transition, the highest ratio ever observed in a light-matter coupled system. Our analysis, based on a microscopic quantum theory, shows that the nonlinear polariton splitting, a signature of this regime, is a dynamical effect arising from the self-interaction of the collective electronic polarization with its own emitted field.     

基于耦合场量子受激拉曼散射的太赫兹波辐射

使用两块长度各为65 mm的MgO:LiNbO3和无掺杂LiNbO3晶体,以1064nm的Q开关Nd:YAG激光器作为抽运光源,在12 mJ/pulse的抽运光能量下得到频率范围为0.34～2.90 THz的电磁辐射.分析表明,激光入射使LiNbO3晶体中具有电磁特性的横光学声子可以和入射光子形成耦合场量子.作为一种电磁特性的元激发,LINbO3晶体的耦合场量子的辐射场频率覆盖部分太赫兹频段范围,并可通过耦合场量子受激拉曼散射过程辐射THz波.根据耦合场量子辐射理论,通过分析晶体的耦合场量子色散特性曲线,可以确定该晶体能否辐射THz波及其带宽范围.     

Interaction of valence band excitations and terahertz TE-polarized cavity modes

The strong coupling of THz radiation and material excitations has potential to improve the quantum efficiency of THz devices. In this paper, we investigate a simple structure delivering THz polaritons and antipolaritons based on valence band transitions. The approach can improve the quantum efficiency of THz based devices based on TE mode in the strong coupling regime of THz radiations and intervalence bands transitions in a GaAs/AlGaAs quantum well. A Nonequilibrium Many Body Approach for the optical response beyond the Hartree–Fock approximation is used as input to the effective dielectric function formalism for the polariton/antipolariton problem. The energy dispersions relations in the THz range are obtained based on simplified analytical approximation.     

The effect of the surface enhanced polariton field on the tunneling current of a STM

The influence of surface polaritons (SPs), excited on the external (fast mode) and internal (slow mode) surfaces of a gold film, on the tunneling current of a STM is investigated. The role of the surface polaritons is directly demonstrated by the angular excitation spectra of the induced tunneling current. Possible mechanisms which might give rise to the SP induced change in the tunneling current are discussed. An electromagnetic field of SPs within a tunneling gap is estimated to be surface enhanced in order to explain the value of the induced tunneling current. Images of the polariton induced signal distribution over the sample surface taken by means of different SP modes are compared in order to obtain information on the structure of the internal surface of the film.     

Back-propagating surface polaritons of a one-dimensional photonic crystal containing single negative metamaterials

The existence of the surface polaritons at the interface separating a semi-infinite uniform left-handed metamaterial and a one-dimensional photonic crystal composed of alternating layers of two kinds of single-negative materials is theoretically investigated. The dispersion characteristics of the surface polaritons are analyzed and demonstrated that in the presence of metamaterial, the surface polaritons are sensitive to light polarization, so that there exist only backward TM-polarized (or TE-polarized) kind of the surface polaritons depending on the ratio of the thicknesses of the two periodic stacking layers. The existence regions of the surface polariton modes are determined for both TM-polarized and TE-polarized surface polariton modes.     

含单负材料三明治结构的电磁隧穿特性

在理论分析的基础上,结合实验研究了单负材料/正折射率材料(或单负材料)/单负材料三明治结构的电磁隧穿性质.这种结构的电磁隧穿来源于入射平面波与结构的表面或体极化激元的耦合,从理论上讨论并计算了正入射情况下这种结构中的极化激元的色散关系.发现:由单负材料作为边界而正折射率材料为中间层的三明治结构具有体极化激元,这种极化激元的共振频率随着中间层厚度的增加向低频移动;由不同性质的单负材料构成的三明治结构具有两条色散曲线,这两条色散曲线随着中间层厚度的增加而简并.随后基于L-C传输线技 关键词： 单负材料 极化激元 隧穿 L-C传输线')" href="#">L-C传输线     

Aspects on Applications of IR Reflectivity- and Raman Scattering-Experiments on Polaritons in Solid State Chemistry and Biophysics

The coupled phonon-photon state called “polariton” is an elementary excitation which exists at all temperatures in single crystalline materials with well defined translational symmetries. In the view of this aspect polaritons turn out to be more important for the dynamics of crystal lattices in general than e.g. magnons or plasmons which normally can be excited only in certain low temperature ranges. The present article summarizes experimental results which all might be applied as analytical methods. An improved method for the determination of fundamental mode frequencies is described. Polariton interactions with localized modes, and second order phonons and the relation to the ferroelectric phase transition mechanism is reviewed. Furthermore experiments concerning parametric light scattering, the TM-reflection technique, the ATR-method, and nonlinear optical experiments are summarized. We finally discuss the question of mechanical-electromagnetic energy conversion and some tentative future aspects.     

Research progress of femtosecond surface plasmon polariton

As the combination of surface plasmon polariton and femtosecond laser pulse,femtosecond surface plasmon polariton has both nanoscale spatial resolution and femtosecond temporal resolution,and thus provides promising methods for light field manipulation and light-matter interaction in extreme small spatiotemporal scales.Nowadays,the research on femtosecond surface plasmon polariton is mainly concentrated on two aspects:one is investigation and characterization of excitation,propagation,and dispersion properties of femtosecond surface plasmon polariton in different structures or materials;the other one is developing new applications based on its unique properties in the fields of nonlinear enhancement,pulse shaping,spatiotemporal super-resolved imaging,and others.Here,we introduce the research progress of properties and applications of femtosecond surface plasmon polariton,and prospect its future research trends.With the further development of femtosecond surface plasmon polariton research,it will have a profound impact on nano-optoelectronics,molecular dynamics,biomedicine and other fields.