Enhancing circular dichroism by super chiral hot spots from a chiral metasurface with apexes
Teh, Bing Hong
Date of Issue2017
School of Physical and Mathematical Sciences
Centre for Disruptive Photonic Technologies
Manipulating light spin (or circular polarization) is an important research field and may find broad applications from sensors, display technology, to quantum computing and communication. To this end, planar metasurfaces with larger circular dichroism are strongly demanded. However, current planar chiral metasurface structures suffer from either fabrication challenge, especially from near-infrared to visible spectrum, or insufficient circular dichroism. Here, we report a chiral metasurface composed of achiral nanoholes which allow for precisely creating apexes in the designed structure. Our investigation indicates that the apexes act as super chiral hot spots and enable the highly concentrated near-field optical chirality leading to a remarkable enhancement of circular dichroism in the far-field. A 4-fold enhancement of the circular dichroism and a strong optical activity of ∼15 degrees have been experimentally achieved. Besides the enhanced chirality, our design genuinely overcomes the nanofabrication challenge faced in existing planar chiral metasurfaces.
Applied Physics Letters
© 2017 American Institute of Physics (AIP). This paper was published in Applied Physics Letters and is made available as an electronic reprint (preprint) with permission of American Institute of Physics (AIP). The published version is available at: [http://dx.doi.org/10.1063/1.4984920]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.