Reconfiguring Stabilized 3D Soft Photonic Crystals Toward Holography With Broadband Tunability and Wide Viewing Angles

ABSTRACT Liquid crystalline blue phase (BP), as an elegant example of soft photonic crystals (PCs) with cubic symmetry, has garnered widespread attention in both fundamental science and practical applications. This is not only due to its selective reflection for circular polarized light (CPL), but also because the 3D photonic structure enhances the degree‐of‐freedom for multiplexed optical modulation. Recent progress has witnessed a plethora of BPs applied to lasers, optical encryption, and holography. However, in these scenarios, combining wide‐spectral tunability with long‐term stability remains challenging. Here, by electrically reconfiguring stabilized BP crystals with tailored orientations, we demonstrate CPL‐selective holograms with tunable reflection covering the entire visible range; we further verify that, owing to their inherent 3D chiral photonic structure, BPs exhibit excellent spectral monochromaticity with full width at half maximum (FWHM) < 36 nm, wide range of reflection angle (−55°–+55°), and smaller angular dependence compared to cholesteric liquid crystals (CLCs) with classical 1D photonic structures, facilitating the achievement of holograms of next generation with stable colors and wide viewing angles. Our work is anticipated to provide insights into the photonic nature of BPs in soft condensed matter, and also promote the progress of soft crystals in advanced photonics.