Polarization-directed growth of spiral nanostructures by laser direct writing with vector beams

Chirality is pivotal in nature which attracts wide research interests from all disciplines and creating chiral matter is one of the central themes for chemists and material scientists. Despite of significant efforts, a simple, cost-effective and general method that can produce different kinds of chiral metamaterials with high regularity and tailorability is still demanding but greatly missing. Here, we introduce polarization-directed growth of spiral nanostructures via vector beams, which is simple, tailorable and generally applicable to both plasmonic and dielectric materials. The self-aligned near field enhances the photochemical growth along the polarization, which is crucial for the oriented growth. The obtained plasmonic chiral nanostructures present prominent optical activity with a g-factor up to 0.4, which can be tuned by adjusting the spirality of the vector beams. These spiral plasmonic nanostructures can be used for the sensing of different chiral enantiomers. The dielectric chiral metasurfaces can also be formed in arrays of sub-mm scale, which exhibit a g-factor over 0.1. However, photoluminescence of chiral cadmium sulfide presents a very weak luminescence g-factor with the excitation of linearly polarized light. A number of applications can be envisioned with these chiral nanostructures such as chiral sensing, chiral separation and chiral information storage. Chiral nanostructures are in demand for various applications, but facile and scalable fabrication is a technical challenge. Here, the authors report polarization-directed chiral growth of complex spiral patterns by laser direct writing with vector beams.

Automated summary

Chirality is important in nature and researchers in various disciplines are interested in creating chiral matter. A method for producing different kinds of chiral metamaterials with high regularity and tailorability is still lacking. In this study, the authors introduce a polarization-directed growth method for spiral nanostructures using vector beams, which is simple and applicable to both plasmonic and dielectric materials. The obtained plasmonic chiral nanostructures show significant optical activity and can be used for sensing different chiral enantiomers.