金属异质波导阵列中的表面等离激元传播特性

提出了一种新的一维金属异质波导阵列的设计方案,即波导芯区周期调制的金属波导阵列.数值模拟的结果表明,金属波导芯区的周期调制引起波导中传播的表面等离激元有效折射率的周期调制,从而可在特定的波段打开一个表面等离激元带隙(如1550nm附近).通过引入合适的缺陷波导单元,可获得特定波长的高品质因子(Q=556)的表面电磁模共振.这一结果可用于设计亚波长的布拉格反射器、光发射器、滤波器等,有可能被用于未来的集成光路.     

基于表面等等离波子的新型Y分支波导

新型高效的纳米光波导器件的研制纳米集成光学的核心技术之一。Y分支波导作为最基本的分光和光路连接元件是纳米光学器件设计与制备的基础。运用时域有限差分(FDTD)法,模拟计算了基于表面等等离波子(SPP)的纳米Y分支波导的传输特性。结果表明,该新型Y分支波导在光通信波段可以实现大角度的分光功能,且在180°分支情况下,传输效率仍高达92.8%以上。另外,该波导还具有导波性能良好、对分叉处间隙缺陷大小不敏感及制作容差较大和器件尺寸在纳米量级等特点。对该新型光波导器件的研究为未来纳米集成光学器件的研制和应用有一定的指导意义。     

表面等离子体共振控制镜面反射率

对金属介电常数随温度变化的计算进行了修正,提出了利用表面等离子体共振(SPR)实现温度控制镜面反射率的方法。在Kretschmann结构中的金属膜上涂覆热光系数较大的聚合物材料,考虑该结构中各种材料介电常数以及金属膜厚度随温度的变化,利用特征矩阵法进行了数值模拟,得到SPR反射率曲线随温度的变化。模拟结果显示,当波长为532nm的p偏振光分别以70°和75°入射时,在10℃～90℃范围内调节温度,可实现反射率在52.8%～41.5%和31.1%～18.8%范围内的调节。     

干涉高斯光诱导的表面等离子激元驻波场的分析

考虑到实际入射光强的空间分布不均匀,基于Kretschmann模型并采用角谱方法分析模拟了两束高斯光干涉诱导表面等离子激元(SPP)驻波场。与理想平面波不同,高斯光诱导的SPP干涉条纹幅值大小不等,分布复杂,这表明光强空间非均匀程度会严重地影响到曝光深度的分布。还分析了金属薄膜的厚度、损耗以及光刻胶的介电常数对SPP驻波场的影响,并得出不恰当的金属板厚和细微损耗都会极大削弱SPP驻波场,而如果光刻胶的介电常数过大则有可能产生不了表面等离子体共振的结论。     

Duality of Spoof Surface Plasmon Polaritons on the Complementary Structures of Ultrathin Metal Films

Complementary metal structures manifest a remarkable scattering feature, known as Babinet's principle. Meanwhile, for surface modes confined to one or two dimensions, the relation between the modes on complementary structures has not been thoroughly studied. Here, spoof surface plasmon polaritons supported on complementary metal films are systematically investigated. The duality of electromagnetism guarantees that these surface modes on complementary metal films possess precisely the same dispersion regardless of the geometry of the grooves, which is confirmed by both numerical simulations and experimental measurements. This work may open another avenue for spoof surface plasmon polaritons in both the theoretical and practical aspects.     

Otto结构加载MIM波导的表面等离子激元传输与衰减特性

设计了加载MIM波导的Otto结构研究SPPs的传输和衰减特性,应用球面EM场的解法求解了整个介质区域的本征函数的特征值。对SiO₂厚度分别为750 nm和1 500 nm的设计结构进行了仿真,结果表明:750 nm改进结构的TM₀传播常数达到了1.541,衰减系数仅仅为2.80;随着SiO₂层介质厚度的减小,反射系数随之增大,且不同金属介电常数的谐振方向变化趋势一致;随着腔厚度的减小,在反射相位减少的同时其存储能量也随之减少。     

五层对称人工超常材料结构的表面等离子体激元

研究了由左手材料、负介电材料、常规介电材料所构成的几种五层对称结构表面等离子体激元的特性.讨论了表面等离子体激元的存在区域、色散关系、以及p和s偏振的表面色散曲线枝,发现表面模的性质强烈依赖于系统的组成材料及其组合方式|层数越多,表面色散曲线枝也越多,处在频率通带的表面极化模态也越多|在五层结构中有p和s两种偏振的表面等离子体激元,在共振时,可导致p波和s波强透射.此外,通过使用衰减全反射方法,探讨了激发并观察表面等离子体激元的可能性.     

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.     

三层不对称人工电磁材料界面处表面等离子体激元的理论研究

从P和S偏振出发.研究了由常规材料/左手材料/负介电常数材料、及常规材料/左手材料/负磁导率材料这两种三层不对称结构界面上表面等离子体激元(Surface plasmon polaritons,SPPs)的存在区域、色散曲线及其激发.观察到表面等离子体激元的性质强烈地依赖于人工电磁材料的组成参量,例如介质板的厚度和等离子体的频率.最后,使用衰减全反射(Attenuated total reflection,ATR)技术,探究了激发和观察表面等离子体激元的可能性.并针对P和s偏振两种情况计算了衰减全反射光谱.     

Surface Plasmon Resonance of Au Nanoparticles Fabricated by Negative Ion Implantation and Grid Structure toward Plasmonic Applications

Optical properties of Au nanoparticle composites and a grid structure of Cu nanoparticle composite were studied. Negative ion implantation was applied to synthesize Au and Cu nanoparticles in amorphous SiO₂ and Al₂O₃. Au nanoparticles were embedded within a depth of 30 nm by 60keV Au⁻ implantation. The surface plasmon resonance (SPR) of Au:SiO₂ and Au: Al₂O₃ composites shifted to red and to blue, respectively, compared to calculated ones by the Mie theory. Optical nonlinearity was measured with pump-probe femtosecond spectroscopy and the transient spectrum of Au: Al₂O₃ composite presented a large red shift from the SPR peak. Image mapping of far-field transmitted intensity of Cu-implanted SiO₂ with a fine grid structure drawn by laser-lithography was observed by a scanning near-field optical microscopy (SNOM) system.     

表面等离子激元与F-P共振耦合平衡钙钛矿太阳能电池有源层内载流子产生速率

为提高有机-无机杂化钙钛矿太阳能电池（PSCs）光吸收效率、平衡有源层中载流子产生速率,将周期性纳米光栅结构引入到PSCs器件结构中。分析了光栅周期、光栅高度和有源层厚度对表面等离子激元（SPPs）与法布里-珀罗（F-P）共振耦合模式的影响。通过改变光栅周期,实现了SPPs与F-P共振耦合波长范围与钙钛矿材料的弱吸收光谱区域相重合,同时光栅高度的增加可以增大耦合模式的光谱宽度。SPPs与F-P共振耦合模式实现了金属电极与电子传输层（ETL）界面处的局域电场增强。结果表明:场增强效应扩展到有源区,有效提高了PSCs有源层远入射光侧在570~800 nm波长范围内的光吸收,进而提高了有源层远入射光区域的载流子产生速率。当光栅周期为250 nm、光栅高度为50 nm、源层厚度为300 nm时,PSCs在太阳光弱吸收光谱区域内的本征吸收提高了~12%,有源层远入射光侧载流子产生速率提高了~41%。     

角反射器耦合的InGaAs应变层量子阱锁相列阵激光器的模式特性

采用反应离子刻蚀技术，设计、制备了一种角反射器耦合的１０单元ＩｎＧａＡｓ应变层单量子阱镇相列阵激光器。在高达４×Ｉｔｈ的工作电流范围内，获得了主单瓣远场输出，单瓣束宽最低达０．６４°，接近衍射极限。考虑了角反射器引入的纵模与侧模之间的耦合，及载流子注入引起的反折射率导引，用微扰理论作了模拟计算，表明角反射器耦合是锁相列阵的一种新的耦合机制；主瓣对应于同相锁定，支瓣是由周期性微扰引入的高阶本征模。     

Long-Range Surface Plasmon Polaritons Guided by a Thin Metal Stripe

A long-range surface plasmon polariton （LRSPP） waveguide consisting of a 15nm thick gold stripe embedded in a homogeneous polymer BCB is reported. LRSPPs are excited by TM-mode input light successfully using an end-fire method. By scanning the output coupling fibre, the near field of the LRSPP is measured. The propagation loss of as low as 2.34 dB/mm is demonstrated.     

基于侧边抛磨光纤表面等离子体共振的折射率和温度传感研究

用轮式侧边抛磨法制作侧边抛磨光纤,通过磁控溅射法溅射金膜制成侧边抛磨光纤表面等离子体共振(SPR)传感器,并通过理论和实验对传感器的折射率灵敏度以及温度特性做了深入研究。结果表明表面等离子体共振波长随待测样品折射率的增大向长波长方向漂移,平均折射率灵敏度为4.1×103 nm/RIU(RIU为单位折射率),高于已报道的结果;共振波长随待测样品温度的升高向短波长方向漂移,平均温度灵敏度为0.36nm/℃,故该光纤SPR传感器具有更强抗温度漂移能力和更高的高折射率灵敏度,其在生物化学传感领域有重要的应用。     

一种基于相位测量的角漂移自适应结构表面等离子体共振气体折射率测量系统

提出了一种可抑制角漂移的表面等离子体传感器结构,并结合相位测量设计了相应的气体折射率测量系统。分析表明激光入射角、金膜厚度以及反射光p、s分量的相位差与气体折射率之间的固有非线性是影响相位响应度与折射率测量精度的主要因素。计算表明所提出的自适应结构将角漂移引起的误差降低了一个数量级并很大程度提高了测量灵敏度。同时分析设计了金膜厚度参数,并评估了反射光p、s分量的相位差与气体折射率之间固有非线性带来的误差。应用于空气折射率的测量比对实验显示其测量精度达到了10-6量级。     

Propagation Characteristics of Surface Plasmon Polaritons Near Anisotropic 2D Materials Sandwiched by Chiral Media

A novel surface plasmonic waveguide structure composed of chiral medium and 2D material is proposed. The universal direction-dependent dispersion relation is obtained, which covers the combinations between 2D materials with in-plane isotropy or anisotropy and the surroundings with or without chirality. The tunability of the behavior of surface plasmon polaritons with the chirality of environment and the doping level are investigated. The averaging effect of chirality in both sides of 2D material is unveiled. Besides, the transverse spin of SPPs in the Chiral-2D material structure is explored and the asymmetric distribution of the transverse spin depends mainly on the contribution from the magnetic spin instead of the electric spin. These features are advantageous for the manufacture of novel photonic devices and the development of sensors techniques for the chiral environment.     

Planar Spoof Surface Plasmon Polariton Antenna by Using Transmissive Phase Gradient Metasurface

Spoof surface plasmon polariton (SSPP) antennas are of particular importance in communication and radar systems. Currently available SSPP radiation devices are limited to low performance with high side-lobes because it is extremely challenging to accurately control the wave vector of SSPP and the inherent momentum mismatch between the SSPP and spatial waves. Inspired by the optical principle of reversibility, high-performance radiation control of SSPP is proposed to be achieved with transmissive phase gradient metasurface (TPGM). The TPGM, placed a meticulously optimized distance above the SSPP propagation structure, can provide an additional opposite wave vector to match the momentum between the SSPP and spatial waves. When the propagating SSPP transmits on the TPGM, it can be decoupled into the free space accurately and flexibly. Numerical results coincide well with the measurements, indicating that the radiation control of SSPP achieves high-performance and low side-lobe within 9 to 10.5 GHz with the measured radiation efficiency higher than 50%. The measured maximum efficiency appears at 9.8 GHz for 69%. Thanks to the flexible and accurate manipulation of the dispersion relation of SSPP provided by TPGM, the findings may open an avenue in achieving larger angle scanning antenna.     

测量金属膜粗糙度的表面等离子激元光谱方法

介绍了确定金属膜表面粗糙度的表面等离子激元光谱方法。测量了二种银膜在表面等离子激元激发条件下的光散射强度分布。通过与理论计算的拟合，得到了描写这二种银膜／空气同粗糙界面的特征参数。     

银-光子晶体-银结构中两Tamm等离子体极化激元的耦合

利用传输矩阵研究了银-光子晶体-银结构中两Tamm等离子体极化激元(TPPs)的耦合态。我们的数值结果表明当光子晶体的周期数n10时,存在两本征波长相同的非耦合Tamm等离子体极化激元(非耦合TPPs),当n≤10时,两非耦合Tamm等离子体极化激元发生耦合,劈裂成两本征波长不同的耦合Tamm等离子体极化激元。随着n的减小,两耦合Tamm等离子体极化激元(耦合TPPs)间的劈裂能量增大,当n=3时,劈裂能量达到287.5meV。从银-光子晶体-银结构中的实时电场分布可以得到:本征波长较长的耦合TPP由两非耦合TPPs对称耦合产生,而本征波长较短的耦合TPP由两非耦合TPPs反对称耦合产生。