The Chiral Property of Anisitropic Gold Metamaterials

The Invention of metamaterials offers unprecedented opportunities in realizing novel functional devices including optical switches, transducers, modulators, filter and phase shifter. The realization of metamaterials can be made from top-down and bottom up, either from lithographic methods such as EBL or self-assembly using predefined scaffolds (eg. DNA) for arranging designed nanoparticle coupling and shapes. However, significant challenge exists in controlling symmetry functions directly by the growth. Here we show that the anisotropy within one nanoparticle can be controlled directly for realizing important metamaterials functions. As a result, the anisotropy of gold nanoparticle has been realized for the first time. The symmetry of anisotropy can be controlled by the size and arm ratio of nano-stars, leading to strong chirality. This work provides a new materials platform for symmetry control in nanoparticle metamateials leading to the properties and applications previously deemed unfeasible