Enhanced circular dichroism of double L-shaped nanorods induced by gap plasmon coupling

Chirality is important in the fields of science and engineering. In comparison to 3D nanostructures, planar nanostructures have a great advantage of easy fabrication. However, previous studies on planar chiroptical effects were limited by the mechanism of enhancing the CD effect. In this paper, a narrow gap is designed between two single planar L-shaped nanorods to facilitate gap plasmon coupling and induce the splitting of the quadrupole mode. This splitting can enhance the circular dichroism (CD) effect. Simulated results also proclaim that CD properties are manipulated by geometrical parameters. The structural design and the new mechanism of the CD effect may provide a novel method for chiral manipulations of light and chiral optical devices.