Ermolaev Georgy A, Voronin Kirill V, Toksumakov Adilet N, Grudinin Dmitriy V, Fradkin Ilia M, Mazitov Arslan, Slavich Aleksandr S, Tatmyshevskiy Mikhail K, Yakubovsky Dmitry I, Solovey Valentin R, Kirtaev Roman V, Novikov Sergey M, Zhukova Elena S, Kruglov Ivan, Vyshnevyy Andrey A, Baranov Denis G, Ghazaryan Davit A, Arsenin Aleksey V, Martin-Moreno Luis, Volkov Valentyn S, Novoselov Kostya S
Emerging Technologies Research Center, XPANCEO, Dubai Investment Park First, Dubai, United Arab Emirates.
Donostia International Physics Center (DIPC), Donostia/San Sebastián, 20018, Spain.
Nat Commun. 2024 Mar 6;15(1):1552. doi: 10.1038/s41467-024-45266-3.
Nature is abundant in material platforms with anisotropic permittivities arising from symmetry reduction that feature a variety of extraordinary optical effects. Principal optical axes are essential characteristics for these effects that define light-matter interaction. Their orientation - an orthogonal Cartesian basis that diagonalizes the permittivity tensor, is often assumed stationary. Here, we show that the low-symmetry triclinic crystalline structure of van der Waals rhenium disulfide and rhenium diselenide is characterized by wandering principal optical axes in the space-wavelength domain with above π/2 degree of rotation for in-plane components. In turn, this leads to wavelength-switchable propagation directions of their waveguide modes. The physical origin of wandering principal optical axes is explained using a multi-exciton phenomenological model and ab initio calculations. We envision that the wandering principal optical axes of the investigated low-symmetry triclinic van der Waals crystals offer a platform for unexplored anisotropic phenomena and nanophotonic applications.
自然界中存在着丰富的材料平台，这些平台具有因对称性降低而产生的各向异性介电常数，并呈现出各种非凡的光学效应。主轴是这些定义光与物质相互作用的效应的基本特征。它们的方向——使介电常数张量对角化的正交笛卡尔基，通常被认为是固定的。在这里，我们表明，范德华二硫化铼和二硒化铼的低对称三斜晶体结构的特征是，在空间波长域中，面内分量的主轴旋转超过π/2度。相应地，这导致了其波导模式的波长可切换传播方向。利用多激子唯象模型和从头计算解释了主轴漂移的物理起源。我们设想，所研究的低对称三斜范德华晶体的主轴漂移为未探索的各向异性现象和纳米光子应用提供了一个平台。
