Near-infrared chirality of plasmonic metasurfaces with gold rectangular holes

Chirality is a fundamental property of nature, which represents an important asymmetrical feature in several disciplines. Nowadays, chiral response has potential applications in many fields. Here, we systematically investigate near-infrared chirality of a novel plasmonic chiral metasurface consisting of rectangular holes. The strong circular dichroism with 0.76 can be achieved in the near-infrared wavelength. By studying the influence of the metasurface structure parameters on circular dichroism (CD), the results clearly show that the period is smaller than the wavelength when triggering the chirality. Besides, CD is strongly dependent on the rotation angle of the resonance units. Thus, it is possible to effectively invert the circular dichroism and regulate the chirality through changing the orientation of units. Furthermore, the distributions of electric field under incident circularly polarized (CP) waves have been calculated to reveal the underlying mechanism. We believe that this work will lay the theoretical foundation for chiral metasurfaces design and promote the development of chirality.Graphical abstract Chirality of plasmonic metasurfaces is investigated, which is closely related to the orientation of resonance unit.