Bidirectional Origami Inspiring Versatile 3D Metasurface

Micro/nano origami is a fascinating 3D fabrication technology, showing a strong ability to control structural space degrees of freedom, but which are usually only able to achieve single-direction origami and hence its controlling spatial orientation is still limited to a certain extent. Here, the bidirectional origami induced by focused ion beam irradiation is proposed to break through the freedom of structural space control and realize challenging 3D micro/nanofabrication. It is found that the FIB-induced bidirectional deformation mainly relies on both materials and the ion doses, and the deformation degrees can be tuned by ion irradiated doses, which greatly contributes to construct large numbers of diverse 3D structures. Further, the underlying physics of FIB induced origami are discussed by Monte Carlo simulations along with experiments to reveal that the amounts of atoms sputtering determines the initial direction of deformation. This bidirectional origami exhibits unique capabilities in design and fabrication of versatile 3D metasurface devices. With this strategy, a 3D chiral metasurface composed of an array of bidirectional folded split ring resonators is achieved, showing a giant circular dichorism as high as 0.78/0.85 (Experiment/Simulation) in the mid-infrared region. Such powerful bidirectional origami paves high efficiency approach to broaden 3D micro/nano photonics device.