高性能表面等离激元慢光和无衍射器件的设计研究

Slow light technology of surface plasmon polaritons(SPPs), one of the key technologies of the nanoscale integrated all-optical networks, has attracted great interest. The research of slow SPPs devices has got great progress in recent years. However, the further improvement of the performance of the slow SPPs devices are restricted by the intrinsic absorption loss of metal in optical region. Reasonable design method which can reduce the intrinsic influence of metal and further improve the performance of slow SPPs devices has been an important link of being pratical of slow SPPs devices. The propagation loss of SPPs can be reduced by the nondiffractive technology, and the performance of the all-optical networks will be greatly improved if the SPPs nondiffractive technology will be realized in nanoscale integrated optical devices in the future. So in this project, we will carry out the study of design high performance SPPs slow light and nondiffraction devices , which are two important devices used in furture all-optical networks. The research content is divide into two parts. In first part, we will redesign dual-channel slow SPPs device which we proposed before, and several new slow SPPs devices with supersmall size along the propagation direction will be obtained through replacing the Bragg reflectors by very thin metal walls. Two key properties of transmission type slow SPPs devices, transmission efficiency and normalized delay bandwidth product, will be improved by the new design method. In the second part, we will study the structure composed of different nanoscale metal waveguide arrays in tandem, and obtain nondiffraction SPPs devices with high transmission efficiency. All the studies not only have a certain academic value, but also have an important guidance meaning of making the laboratoy devices to be pratical devices.

表面等离激元（SPPs）慢光技术是纳米集成全光网络的核心技术之一，对它的研究引起了广泛兴趣并取得了重大进展。但光波段金属的吸收损耗制约了SPPs慢光器件性能的提高，减小金属固有影响、提高器件性能的合理的设计方法是慢光器件走向应用的重要环节。SPPs无衍射技术可降低传输损耗，特别是在纳米光集成器件中实现SPPs无衍射传播可大大提高全光网络的性能。本项目拟设计研究在纳米全光网络中有重要应用的高性能SPPs慢光和无衍射器件。首先，在我们前期提出的双波段SPPs慢光器件基础上进行改进，用薄金属壁代替结构中的Bragg反射器，设计多种在传播方向上尺度超小的新型慢光器件结构，提高透射型SPPs慢光器件的传输效率、归一化延迟带宽积等制约其实用化的关键性能；其次，研究纳米金属波导阵列串联耦合系统，设计高传输效率的集成SPPs无衍射器件。这些研究不仅具有一定的学术价值，而且为两种器件的实用化奠定一定的基础。

以慢光技术为代表的光缓存、光存储等是未来芯片以光子技术取代电子技术实现全光网络的核心技术之一，另外在纳米集成光器件中实现抑制光传播衍射，将大大提高光网络的传输性能。本项目开展研究如下：1)设计了超紧凑型的表面等离激元（SPPs）慢光器件（沿传播方向的几何长度为1.6μm），工作带宽高达37THz，同时涵盖了1310和1550nm两通讯波段，归一化延迟带宽积高达0.44，6倍于最近报导的数值0.071。2) 设计了超紧凑型光学超晶格结构，在具有某些结构参数的超晶格中可激发3个不同THz频率的Bloch振荡，而在某些特定结构参数的超晶格结构利用共振Zener隧穿效应，可在2THz的工作带宽内实现只有1/9真空光速的慢光传输。3）研究了金属椭圆纳米环(MENR)颗粒周期阵列的局域表面等离激元共振（LSPR）及折射率传感（RIS）特性，较清晰合理地解释了决定LSPR共振峰位置的三个因素，观察到了点阵衍射导致的增强LSPR峰，并总结出了获得高RIS的颗粒和阵列条件，基于该共振特性的阵列在集成化光学探测仪器设计方面具有一定的应用前景。4) 研究了两不同光栅（光栅常数相同但占空比不同）的Lau效应现象，基于交叉谱密度函数获得两个不同光栅所产生的Lau条纹强度分布函数，在特定条件下，该效应可获得对比较高的条纹，该效应在集成可调分光器件设计方面有一定应用前景。5）研究了两种激发纳米金属电介质波导阵列（NMDWAs）无衍射传播模式的方法，实现降低SPPs在NMDWAs中传播衍射。其一，裁剪入射端面法，入射光垂直于以不同特定角度裁剪的入射端面可分别实现激发第一和第二Brillouin区内的无衍射传播模式。其二，利用辅助NMDWAs调制光波矢法，在辅助NMDWAs与目标NMDWAs间两种不同耦合方式下均实现了激发目标NMDWAs的无衍射模式。