Center for Nanophotonics, FOM Institute AMOLF, Science Park 104, 1098 XG, Amsterdam, The Netherlands.
Nano Lett. 2011 Sep 14;11(9):3779-84. doi: 10.1021/nl201839g. Epub 2011 Aug 3.
Optical nanoantennas mediate optical coupling between single emitters and the far field, making both light emission and reception more effective. Probing the response of a nanoantenna as a function of position requires accurate positioning of a subwavelength sized emitter with known orientation. Here we present a novel experimental technique that uses a high-energy electron beam as broad band point dipole source of visible radiation, to study the emission properties of a Yagi-Uda antenna composed of a linear array of Au nanoparticles. We show angle-resolved emission spectra for different wavelengths and find evidence for directional emission of light that depends strongly on where the antenna is excited. We demonstrate that the experimental results can be explained by a coupled point dipole model which includes the effect of the dielectric substrate. This work establishes angle-resolved cathodoluminescence spectroscopy as a powerful technique tool to characterize single optical nanoantennas.
光学纳米天线在单个发射器和远场之间介导光学耦合，使光发射和接收更加有效。探测纳米天线的响应作为位置的函数需要以已知方向精确定位亚波长尺寸的发射器。在这里，我们提出了一种新颖的实验技术，该技术使用高能电子束作为可见辐射的宽带点偶极子源，以研究由线性排列的 Au 纳米粒子组成的 Yagi-Uda 天线的发射特性。我们展示了不同波长的角度分辨发射光谱，并发现了光的定向发射的证据，该发射强烈依赖于天线被激发的位置。我们证明，实验结果可以通过包括介电基底效应的耦合点偶极子模型来解释。这项工作确立了角度分辨的阴极荧光光谱学作为一种强大的技术工具来表征单个光学纳米天线。
