Circular dichroism of spatially complementary chiral nanostructures

Abstract

Circular dichroism (CD) is widely used in biology, medicine, and physics. Three-dimensional (3D) chiral structures have been extensively studied because of their ability to produce significant CD effects. Previously reported 3D chiral structures are limited due to the complexity of fabrication processes and CD mechanisms. Here, spatially complementary chiral nanostructure (SCCN) arrays, which comprise bottom silver films with zigzag-shaped nanoslit and top complementary silver zigzag-shaped nanowires, are theoretically and experimentally shown to provide the CD effect. SCCN arrays are prepared experimentally by combining electron beam lithography (EBL) with normal electron beam deposition (NEBD) method and by utilizing EBL and NEBD only once. Numerical results demonstrate that localized surface plasmon excited on top complementary silver zigzag-shaped nanowires and surface plasmon polariton excited on bottom silver films with zigzag-shaped nanoslit result in the CD effect of SCCN arrays. In addition, the CD effect can be tuned by changing the width of the top complementary silver zigzag-shaped nanowires. Such type of chiral nanostructures has easy tunability, simple fabrication, and a better understanding of chiral optical response, which provides a new design for spatially chiral optoelectronic devices.