Large three-dimensional photonic crystals based on monocrystalline liquid crystal blue phases

• Published in: Nature communications Vol. 8; no. 1; pp. 727 - 8
• Main Authors: Chen, Chun-Wei, Hou, Chien-Tsung, Li, Cheng-Chang, Jau, Hung-Chang, Wang, Chun-Ta, Hong, Ching-Lang, Guo, Duan-Yi, Wang, Cheng-Yu, Chiang, Sheng-Ping, Bunning, Timothy J., Khoo, Iam-Choon, Lin, Tsung-Hsien
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 28.09.2017; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/1019/1022; 639/624/399/919; Crystal growth; Crystal structure; Crystals; Energy gap; Fabrication; Humanities and Social Sciences; Liquid crystals; multidisciplinary; Periodicity; Phases; Photonic band gaps; Photonic crystals; Science; Science (multidisciplinary); Self-assembly; Single crystals
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-017-00822-y

Although there have been intense efforts to fabricate large three-dimensional photonic crystals in order to realize their full potential, the technologies developed so far are still beset with various material processing and cost issues. Conventional top-down fabrications are costly and time-consuming, whereas natural self-assembly and bottom-up fabrications often result in high defect density and limited dimensions. Here we report the fabrication of extraordinarily large monocrystalline photonic crystals by controlling the self-assembly processes which occur in unique phases of liquid crystals that exhibit three-dimensional photonic-crystalline properties called liquid-crystal blue phases. In particular, we have developed a gradient-temperature technique that enables three-dimensional photonic crystals to grow to lateral dimensions of ~1 cm (~30,000 of unit cells) and thickness of ~100 μm (~ 300 unit cells). These giant single crystals exhibit extraordinarily sharp photonic bandgaps with high reflectivity, long-range periodicity in all dimensions and well-defined lattice orientation. Conventional fabrication approaches for large-size three-dimensional photonic crystals are problematic. By properly controlling the self-assembly processes, the authors report the fabrication of monocrystalline blue phase liquid crystals that exhibit three-dimensional photonic-crystalline properties.