Design of Interactive Metahologram using Liquid Crystallinity

Abstract

The arrays of subwavelength-scaled nanostructures on a surface, often called metasurfaces, have made advances in flat optics because of their potential to display programmable hologram and miniaturize optical components. As previous metasurface systems are passive, however, their practical applications have been impeded. Accordingly, recent efforts have focused on the realization of active metasurfaces that can autonomously switch homographic images upon arrival of triggers via using, for example, phase-change materials, mechanical actuations, and chemical reactions. Nevertheless, the full potential of active metasurface system has yet to be realized due to the limitation of previous approaches, including limited design of nanostructures, complex fabrication process, and slow response. In this work, we propose a simple and versatile design rule to enable dynamically tunable metahologram systems by leveraging the optical anisotropic and stimuli-responsive nature of liquid crystals (LCs). The simplest geometry of LC integrated metasurface (LC-MS) is shown in Fig. 1. The metasurfaces are prepared by designing nanostructures to display two distinct holograms upon illumination of left- (LCP) and right-circularly polarized light (RCP). The LC cells are programmed to transmit LCP and RCP before and after application of stimuli (electric-field, heat, surface pressure, and toxic gas), respectively. We demonstrate the LC-MS to dynamically switch holographic images in response to the triggers [1,2]. These attribute provides insight into the rational design of a new class of metasurfaces that enable their full potential of multifunctional active devices.