Maier Stefan A, Kik Pieter G, Atwater Harry A, Meltzer Sheffer, Harel Elad, Koel Bruce E, Requicha Ari A G
Thomas J. Watson Laboratory of Applied Physics, California Institute of Technology, Mail Stop 128-95, Pasadena, California 91125, USA.
Nat Mater. 2003 Apr;2(4):229-32. doi: 10.1038/nmat852.
Achieving control of light-material interactions for photonic device applications at nanoscale dimensions will require structures that guide electromagnetic energy with a lateral mode confinement below the diffraction limit of light. This cannot be achieved by using conventional waveguides or photonic crystals. It has been suggested that electromagnetic energy can be guided below the diffraction limit along chains of closely spaced metal nanoparticles that convert the optical mode into non-radiating surface plasmons. A variety of methods such as electron beam lithography and self-assembly have been used to construct metal nanoparticle plasmon waveguides. However, all investigations of the optical properties of these waveguides have so far been confined to collective excitations, and direct experimental evidence for energy transport along plasmon waveguides has proved elusive. Here we present observations of electromagnetic energy transport from a localized subwavelength source to a localized detector over distances of about 0.5 microm in plasmon waveguides consisting of closely spaced silver rods. The waveguides are excited by the tip of a near-field scanning optical microscope, and energy transport is probed by using fluorescent nanospheres.
要在纳米尺度上实现用于光子器件应用的光与物质相互作用的控制，将需要能够以低于光的衍射极限的横向模式限制来引导电磁能的结构。这无法通过使用传统波导或光子晶体来实现。有人提出，电磁能可以沿着紧密排列的金属纳米颗粒链在衍射极限以下被引导，这些金属纳米颗粒将光学模式转换为非辐射表面等离子体激元。诸如电子束光刻和自组装等多种方法已被用于构建金属纳米颗粒等离子体波导。然而，迄今为止，对这些波导光学性质的所有研究都局限于集体激发，并且沿等离子体波导的能量传输的直接实验证据一直难以获得。在这里，我们展示了在由紧密排列的银棒组成的等离子体波导中，电磁能从一个局域化的亚波长源传输到一个局域化探测器，传输距离约为0.5微米的观测结果。波导由近场扫描光学显微镜的尖端激发，能量传输通过使用荧光纳米球进行探测。
