Generating vector optical field arrays for laser direct writing chiral nanostructures based on metasurface

Chirality is pivotal in nature and creating chiral matter attracts wide research interests from all disciplines. Despite of significant efforts, a simple, cost-effective method with high regularity and tailorability is still demanding but greatly missing. In this article, a metasurface is designed to generate vector optical field (VOF) arrays which can be used to fabricate three-dimensional (3D) and two-dimensional (2D) chiral nanostructures by laser direct writing (LDW) method. The VOF arrays are constructed by superimposing multiple polarized light beams modulated by the metasurface. Various kinds of 3D intensity-sensitive and 2D polarization-dependent spiral patterns will be realized by covering the central beam and adjusting the polarized characteristics of different beams. By combining geometric phase with propagation phase effectively, the metasurface with sixbeam modulation is designed and its transmission fields are unveiled. A good agreement is obtained between theoretically designed chiral patterns through multi-beam interference and VOF arrays obtained by the metasurface. Furthermore, by this means, the periodic, quasi-periodic arrangement and 3D periodicity of chiral structures will be controllable by changing the number and deflection angle of light beams. This study provides a new prospective method for large-area, cost-effective, simple and fast fabrication of chiral structures. This will accelerate the application process of chiral nanostructures in the fields of optical tweezers, chiral sensing, and chiral information storage, etc.