点反射
物理
拓扑绝缘体
Berry连接和曲率
凝聚态物理
极化(电化学)
光子
不对称
散射
等离子体子
光子学
涡流
光学
几何相位
量子力学
热力学
物理化学
化学
作者
Dia’aaldin J. Bisharat,Daniel F. Sievenpiper
标识
DOI:10.1002/lpor.202200362
摘要
Valley-contrast physics has gained considerable attention, particularly for realizing photonic topological insulators (PTIs) that support reflection-free valley-polarized edge modes (VPEMs) in the absence of inter-valley scattering. It is an open question whether similar robust states can exist in the absence of topological valley phase, i.e., nonvanishing Berry curvature at the valleys. It is shown that a C6υ-symmetric triangular photonic crystal (PhC) inherently exhibits uniform distribution of spatially varying phase vortices, which support a local (limited) version of valley Hall effect (LVHE), where the valley polarization is location defined as opposed to being fixed throughout the bulk. Then it is demonstrated that defect regions with sublattice asymmetry in otherwise a symmetric PhC lead to wave localization and splitting of photons according to their valley index, thus enabling VPEMs along a line defect waveguide. The device is fabricated on a silicon-on-insulator (SOI) slab, and it is characterized at near-infrared frequencies showing robust transmission through sharp bends comparable to valley PTIs. The results present a new perspective to creating valley edge states and outline a new waveguiding mechanism applicable to electromagnetics as well as plasmonics, mechanics, and acoustics.
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