Directional Control of Light with Nanoantennas.

Light manipulation has been widely employed in lighting, display, and energy storage, becoming an inseparable part of human lives. However, the conventional optical devices suffer from the diffraction limit of electromagnetic waves. To overcome the limitation, plasmonic and dielectric nanoantennas are introduced for the control of light direction at nanoscale. The directionality of the nanoantennas stems from their electromagnetic resonance properties or the interference between different resonance modes. The near‐field interaction between the nanoantennas and fluorescent emitters or Raman molecules will generate directional light emission. The directional nanoantennas are widely applied in various fields. Although light manipulation at nanoscale is briefly discussed in several review articles, they are not specifically devoted to directional nanoantennas. A more selective, focused and up‐to‐date review article about light manipulation by directional nanoantennas is deemed necessary because of the rapid development in this field. In this article, the properties and mechanisms of various types of nanoantennas made of plasmonic or dielectric nanostructures are introduced, the current developments of the nanoantennas are summarized, and an outlook for future investigation on directional nanoantennas is offered. It is believed that the directional light control with the nanoantennas will be a flourishing and promising research field in the future. [ABSTRACT FROM AUTHOR]