Globally enhanced chiral field generation by negative-index metamaterials

Abstract

We show that negative-index metamaterials can generate chiral electromagnetic fields, which can be used to enhance molecular chiroptical signals by inducing strong local magnetic fields. Compared to circularly polarized light (CPL), the enhanced chiral field generated by a double-fishnet negative- index metamaterial shows a 3.5-fold enhancement of the volume-averaged optical chirality and possesses the same handedness as that of incident CPL, thereby forming a globally enhanced chiral field. By analyzing near-field configurations, the mechanism of the optical chirality enhancement by double- fishnet negative- index metamaterial is elucidated. We thus anticipate that these metamaterials have potential applications in chiroptical spectroscopy.