Park Haedong, Jo Seungyun, Kang Byungsoo, Hur Kahyun, Oh Sang Soon, Ryu Du Yeol, Lee Seungwoo
School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA, UK.
Department of Chemical and Biomolecular Engineering, Yonsei University, Seoul 03722, Republic of Korea.
Nanophotonics. 2022 Jan 18;11(11):2583-2615. doi: 10.1515/nanoph-2021-0644. eCollection 2022 Jun.
A gyroid crystal possesses a peculiar structural feature that can be conceptualized as a triply periodic surface with a constant mean curvature of zero. The exotic optical properties such as the photonic bandgap and optical chirality can emerge from this three-dimensional (3D) morphological feature. As such, gyroid crystals have been considered as the promising structures for photonic crystals and optical metamaterials. To date, several methods have been proposed to materialize gyroid crystals, including 3D printing, layer-by-layer stacking, two-photon lithography, interference lithography, and self-assembly. Furthermore, the discovery of Weyl points in gyroid crystals has further stimulated these advancements. Among such methods, the self-assembly of block copolymers (BCPs) is unique, because this soft approach can provide an easy-to-craft gyroid, especially at the nanoscale. The unit-cell scale of a gyroid ranging within 30-300 nm can be effectively addressed by BCP self-assembly, whereas other methods would be challenging to achieve this size range. Therefore, a BCP gyroid has provided a material platform for metamaterials and photonic crystals functioning at optical frequencies. Currently, BCP gyroid nanophotonics is ready to take the next step toward topological photonics beyond the conventional photonic crystals and metamaterials. In particular, the intrinsic lattice transformations occurring during the self-assembly of BCP into a gyroid crystal could promise a compelling advantage for advancing Weyl photonics in the optical regime. Lattice transformations are routinely considered as limitations, but in this review, we argue that it is time to widen the scope of the lattice transformations for the future generation of nanophotonics. Thus, our review provides a comprehensive understanding of the gyroid crystal and its lattice transformations, the relevant optical properties, and the recent progress in BCP gyroid self-assembly.
螺旋面晶体具有一种独特的结构特征，可将其概念化为平均曲率为零的三重周期曲面。光子带隙和光学手性等奇特的光学性质可源于这种三维（3D）形态特征。因此，螺旋面晶体被认为是光子晶体和光学超材料的有前途的结构。迄今为止，已经提出了几种实现螺旋面晶体的方法，包括3D打印、逐层堆叠、双光子光刻、干涉光刻和自组装。此外，在螺旋面晶体中发现的外尔点进一步推动了这些进展。在这些方法中，嵌段共聚物（BCP）的自组装是独特的，因为这种软方法可以提供易于制造的螺旋面，特别是在纳米尺度上。BCP自组装可以有效地实现范围在30 - 300 nm内的螺旋面的晶胞尺度，而其他方法要实现这个尺寸范围则具有挑战性。因此，BCP螺旋面为光学频率下的超材料和光子晶体提供了一个材料平台。目前，BCP螺旋面纳米光子学已准备好朝着超越传统光子晶体和超材料的拓扑光子学迈出下一步。特别是，在BCP自组装成螺旋面晶体的过程中发生的固有晶格变换有望为在光学领域推进外尔光子学带来引人注目的优势。晶格变换通常被视为限制因素，但在本综述中，我们认为是时候拓宽晶格变换的范围以用于下一代纳米光子学了。因此，我们的综述全面介绍了螺旋面晶体及其晶格变换、相关光学性质以及BCP螺旋面自组装的最新进展。
