论文标题
通过双拓扑山谷 - 霍尔的第二谐波生成全dielectric光子晶体的扭结模式
Second-harmonic generation via double topological valley-Hall kink modes in all-dielectric photonic crystals
论文作者
论文摘要
非线性拓扑光子学探讨了拓扑阶段和非线性光学领域常见的主题，预计将打开拓扑光子学的新范式。在这里，我们通过在全dielectric光子晶体（PHCS）中通过双拓扑山谷孔模式的非线性相互作用（PHC）展示了第二谐波生成（SHG）。我们首先表明，可以通过在二维Honeycomb PHC中散布相应的DIRAC点，可以在一对频率围绕$ω_0$和$2Ω_0$中创建两个拓扑频率带盖。在两个频率带盖中生成了两个以镜像对称方式放置在一起的PHC之间的脉动型结构域壁界面沿着两个pHC之间的脉冲型域壁界面。重要的是，通过全波仿真和模式分散分析，我们证明可以通过两个带隙内的山谷孔循环模式的非线性相互作用进行可调的双向相匹配的SHG。特别是，通过使用与山谷孔扭结模式的磁性部分相关的stokes参数，我们引入了一种新概念，即SHG方向二色性，它被用来表征用于传感手性分子的光学探针。我们的工作为在全登录材料平台中实现的拓扑保护的非线性频率混合和主动光子设备开辟了新的途径。
Nonlinear topological photonics, which explores topics common to the fields of topological phases and nonlinear optics, is expected to open up a new paradigm in topological photonics. Here, we demonstrate second-harmonic generation (SHG) via nonlinear interaction of double topological valley-Hall kink modes in all-dielectric photonic crystals (PhCs). We first show that two topological frequency bandgaps can be created around a pair of frequencies, $ω_0$ and $2ω_0$, by gapping out the corresponding Dirac points in two-dimensional honeycomb PhCs. Valley-Hall kink modes along a kink-type domain wall interface between two PhCs placed together in a mirror-symmetric manner are generated within the two frequency bandgaps. Importantly, through full-wave simulations and mode dispersion analysis, we demonstrate that tunable, bi-directional phase-matched SHG via nonlinear interaction of the valley-Hall kink modes inside the two bandgaps can be achieved. In particular, by using Stokes parameters associated to the magnetic part of the valley-Hall kink modes, we introduce a new concept, SHG directional dichroism, which is employed to characterize optical probes for sensing chiral molecules. Our work opens up new avenues towards topologically protected nonlinear frequency mixing and active photonic devices implemented in all-dielectric material platforms.
