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arXiv 2407.05908physics.opticscond-mat.mes-hall
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由多层过渡金属二硫化物制成的Z₂拓扑光子绝缘体的实现

Realization of Z$_2$ topological photonic insulators made from multilayer transition metal dichalcogenides

University of Sheffield(谢菲尔德大学);University of York(约克大学)

Tommi Isoniemi, Paul Bouteyre, Xuerong Hu, Fedor Benimetskiy, Yue Wang, Maurice S. Skolnick, Dmitry N. Krizhanovskii, Alexander I. Tartakovskii

AI总结:

本研究利用多层WS₂的优异光学与加工特性,制备出拓扑自旋霍尔光子晶格,验证了近红外光子带隙与畴界单向传播特性,为层状材料基纳米光子器件研究开辟新路径。

摘要:

半导体过渡金属二硫化物(TMDs)的单层材料因其引人关注的光学和电子特性长期以来备受研究兴趣。近来,准体相形式的TMDs凭借其高折射率、大光学各向异性、延伸至可见光波段的宽透明窗口,以及适用于非线性光学的稳定室温激子,开始在纳米光子学领域展现出巨大应用潜力。TMD层可通过范德华力附着于任意衬底,这一特性是实现需要异质集成的复杂光子结构纳米加工的另一关键支撑因素。本研究利用这些优异特性,在剥离于SiO₂/Si衬底上、厚度为50至100 nm的WS₂薄片中,制备了由三角形纳米孔阵列构成的拓扑自旋霍尔光子晶格。借助WS₂晶轴决定的各向异性干法刻蚀,我们获得了高质量的结构。室温反射测量显示,在平凡相和拓扑相中,近红外波段均出现光子带隙。通过圆偏振激光激发,在具有锯齿形和扶手椅形畴界的样品中,我们在实空间验证了沿畴界面的单向传播特性。我们采用有限差分时域(FDTD)模拟对光谱测量结果进行了解释。本研究为基于层状(范德华)材料平台的未来复杂纳米光子器件开辟了道路。

英文摘要:

Monolayers of semiconducting transition metal dichalcogenides (TMDs) have long attracted interest for their intriguing optical and electronic properties. Recently TMDs in their quasi-bulk form have started to show considerable promise for nanophotonics thanks to their high refractive indices, large optical anisotropy, wide transparency windows reaching to the visible, and robust room temperature excitons promising for nonlinear optics. Adherence of TMD layers to any substrate via van der Waals forces is a further key enabler for nanofabrication of sophisticated photonic structures requiring heterointegration. Here, we capitalize on these attractive properties and realize topological spin-Hall photonic lattices made of arrays of triangular nanoholes in 50 to 100 nm thick WS$_2$ flakes exfoliated on SiO$_2$/Si substrates. High quality structures are achieved taking advantage of anisotropic dry etching dictated by the crystal axes of WS$_2$. Reflectance measurements at room temperature show a photonic gap opening in the near-infrared in trivial and topological phases. Unidirectional propagation along the domain interface is demonstrated in real space via circularly polarized laser excitation in samples with both zigzag and armchair domain boundaries. Finite-difference time-domain simulations are used to interpret optical spectroscopy results. Our work opens the way for future sophisticated nanophotonic devices based on the layered (van der Waals) materials platform.

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