Large Circular Dichroism in MDM Plasmonic Metasurface with Subwavelength Crescent Aperture

a metal–dielectric–metal planar chiral plasmonic metasurface is proposed and its circular dichroism (cd) property is numerically studied using finite difference time domain computation. the unit cell of planar plasmonic metasurface consists of crescent apertures that are arranged in a particular orientation. the proposed structure exhibits multiband circular dichroism at near-infrared wavelengths. by changing the orientational symmetry, the structure shows a drastic reduction in the circular dichroism. passive controlling of orientational symmetry shows a systematic change in the sign of the cd. high incident angular tolerance of the planar chiral plasmonic metasurface (pcpm) to about 15° suggests the proposed structure might be useful for cd spectroscopy.