Faculty of Physics, Lomonosov Moscow State University , 119991 Moscow, Russian Federation.
INPAC-Institute for Nanoscale Physics and Chemistry and Department of Physics and Astronomy, KU Leuven , Celestijnenlaan 200 D, B-3001 Leuven, Belgium.
Nano Lett. 2017 Dec 13;17(12):7629-7637. doi: 10.1021/acs.nanolett.7b03624. Epub 2017 Nov 1.
Subwavelength optical resonators and scatterers are dramatically expanding the toolset of the optical sciences and photonics engineering. By offering the opportunity to control and shape light waves in nanoscale volumes, recent developments using high-refractive-index dielectric scatterers gave rise to efficient flat-optical components such as lenses, polarizers, phase plates, color routers, and nonlinear elements with a subwavelength thickness. In this work, we take a deeper look into the unique interaction of light with rod-shaped amorphous silicon scatterers by tapping into their resonant modes with a localized subwavelength light source-an aperture scanning near-field probe. Our experimental configuration essentially constitutes a dielectric antenna that is locally driven by the aperture probe. We show how leaky transverse electric and magnetic modes can selectively be excited and form specific near-field distribution depending on wavelength and antenna dimensions. The probe's transmittance is furthermore enhanced upon coupling to the Fabry-Perot cavity modes, revealing all-dielectric nanorods as efficient transmitter antennas for the radiation of subwavelength emitters, in addition to constituting an elementary building block for all-dielectric metasurfaces and flat optics.
亚波长光学谐振器和散射体极大地扩展了光学科学和光子工程的工具集。通过提供在纳米体积中控制和塑造光波的机会，最近使用高折射率介电散射体的发展产生了高效的平面光学元件，如透镜、偏光器、相移板、颜色路由器和具有亚波长厚度的非线性元件。在这项工作中，我们通过利用局域亚波长光源——孔径扫描近场探针，深入研究了光与棒状非晶硅散射体的独特相互作用。我们的实验配置实质上构成了由孔径探针局部驱动的介电天线。我们展示了如何选择性地激发漏模横向电和磁模，并根据波长和天线尺寸形成特定的近场分布。此外，当与法布里-珀罗腔模式耦合时，探针的透过率会增强，这表明全介质纳米棒不仅是亚波长发射器的高效发射天线，而且是全介质超表面和平面光学的基本组成部分。
