Circular Dichroism in Planar Achiral Plasmonic L-Shaped Nanostructure Arrays

Circular dichroism (CD) can be initially observed in intrinsic chiral structures. It was discovered that CD can also be observed in achiral structures with an oblique incident light beam. In this paper, a metal planar achiral L-shaped nanostructure arrays was proposed, and its CD was investigated using the finite element method. The CD phenomenon is due to extrinsic chirality resulting from the achiral structures with an oblique incident electromagnetic wave. Results show that the L-shaped nanostructure arrays can achieve strong and broad bandwidth CD. In addition, the sign of CD can be reversed through changing azimuthal rotation angle of incident light, and the strength of CD depends strongly on light incident direction.