Original Article

Citation: Light: Science & Applications (2017) 6, e17011; doi:10.1038/lsa.2017.11
Published online 14 July 2017

Three-dimensional chiral microstructures fabricated by structured optical vortices in isotropic material
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Jincheng Ni1, Chaowei Wang1, Chenchu Zhang1, Yanlei Hu1, Liang Yang1, Zhaoxin Lao1, Bing Xu1, Jiawen Li1, Dong Wu1 and Jiaru Chu1

1CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230027, China

Correspondence: Y Hu, Email: huyl@ustc.edu.cn; D Wu, Email: dongwu@ustc.edu.cn

Received 30 August 2016; Revised 18 January 2017; Accepted 9 February 2017
Accepted article preview online 13 February 2017

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Abstract

Optical vortices, a type of structured beam with helical phase wavefronts and ‘doughnut’-shaped intensity distributions, have been used to fabricate chiral structures in metals and spiral patterns in anisotropic polarization-dependent azobenzene polymers. However, in isotropic polymers, the fabricated microstructures are typically confined to non-chiral cylindrical geometry due to the two-dimensional ‘doughnut’-shaped intensity profile of the optical vortices. Here we develop a powerful strategy to realize chiral microstructures in isotropic material by coaxial interference of a vortex beam and a plane wave, which produces three-dimensional (3D) spiral optical fields. These coaxial interference beams are generated by designing contrivable holograms consisting of an azimuthal phase and an equiphase loaded on a liquid-crystal spatial light modulator. In isotropic polymers, 3D chiral microstructures are achieved under illumination using coaxial interference femtosecond laser beams with their chirality controlled by the topological charge. Our further investigation reveals that the spiral lobes and chirality are caused by interfering patterns and helical phase wavefronts, respectively. This technique is simple, stable and easy to perform, and it offers broad applications in optical tweezers, optical communications and fast metamaterial fabrication.

Keywords:

chiral microstructure; coaxial interference; optical vortex; two-photon fabrication