Control of ultrafast plasmonic structures by a metal-insulator transition

摘要ECCS-0801985R。范德比尔特大学哈格伦德目标：这个项目的目标是展示VO2中的可逆半导体到金属的转变(SMT)如何调制复合金属-VO2纳米结构中的等离子体激元动力学。智能优点：SMT将通过使用扫描探头尖端的局部绝热加热和使用标准棱镜耦合方案的超快激光激励来启动。利用飞秒泵浦探测光谱学、等离子体显微镜和一种新的、用于探测等离子体传播的双无孔扫描探针尖端方案，将跟踪等离子体激元的动力学。在第一年，我们将测量超快局域表面等离子体共振(LSPR)响应和表面等离子体激元(SPP)在由双层薄膜(VO2上的Ag或Au)和VO2覆盖的纳米颗粒阵列(Ag或Au)组成的纳米孔阵列上的传播。第二年，我们将制备各种VO2：金属复合纳米结构，如非球形纳米粒子、纳米螺旋粒子和带有凹槽衍射结构的纳米孔。我们将研究局部曲率、尺寸和形态以及线偏振光和圆偏振光激发对LSPR和SPP动力学的影响。在第三年，我们将制备纳米颗粒链(Au-VO2-Au？椭球链和Au-Au？由VO2覆盖的链)和纳米线或纳米通道几何形状。由于诱导磁化、极化和色散，这些SPP引导结构有望表现出有趣的效应，这些效应将通过它们在可见光光谱中的签名来跟踪。这些实验将为调制SPP在纳米结构中的传播指明了方向，这些纳米结构可以作为各种等离子激元装置的原型。更广泛的影响：这项技术将展示近红外通信频段的超高速宽带开关。对等离子体-光子耦合和等离子体动力学的基本了解有望产生工业“副产品”效益。此外，该项目还将通过在国际、跨机构协作环境中对初级科学家进行培训，以及将向科学界提供的纳米等离子网络研究生研讨会课程，来传播新知识。

ABSTRACT ECCS- 0801985R. Haglund, Vanderbilt UniversityObjective: The objective of this project is to show how plasmon dynamics in composite metal-vanadium dioxide (VO2) nanostructures can be modulated by the reversible semiconductor-to-metal transition (SMT) in VO2. Intellectual Merit: The SMT will be initiated by localized adiabatic heating using a scanning-probe tip, and by ultrafast laser excitation using standard prism coupling schemes. Plasmon dynamics will be tracked using femtosecond pump-probe spectroscopy, plasmon microscopy and a novel, dual apertureless scanning-probe tip scheme for detecting plasmon propagation. During the first year, we will measure the ultrafast localized surface-plasmon resonance (LSPR) response and surface plasmon-polariton (SPP) propagation on nanohole arrays comprising bi-layer films (Ag or Au on VO2) and on VO2-covered nanoparticle arrays (Ag or Au). In the sec-ond year, we will fabricate various VO2:metal composite nanostructures such as non-spheroidal nanoparticles, nanospirals and nanoholes surrounded by grooved diffractive structures. We will investigate the effects of local curvature, size and morphology, and of excitation by linearly and circularly polarized light, on LSPR and SPP dynamics. In the third year, we will fabricate SPP waveguides such as nanoparticle chains (Au-VO2-Au ? ellipsoidal chains and Au-Au ? chains capped with VO2) and nanowire or nanochannel geometries. These SPP-guiding structures are expected to exhibit interesting effects due to induced magnetization, polarization and dispersion that will be tracked via their signatures in the visible optical spectrum. These experiments will point the way to modulating SPP propagation in nanostructures that could serve as prototypes for a variety of plasmonic devices. Broader Impact: The technology will be a demonstration of an ultrafast broadband switch in the near-infrared communications spectral bands. The fundamental understanding of plasmon-photon coupling and plasmon dynamics is expected to result in industrial "spin-off" benefits. Ad-ditionally, the project will result in the dissemination of new knowledge through the training of junior scientists in an international, cross-institutional collaborative environment and a web-based graduate seminar course in nanoplasmonics that will be available to the scientific com-munity.