Design of broadband all-dielectric valley photonic crystals at telecommunication wavelength
Design of broadband all-dielectric valley photonic crystals at telecommunication wavelength
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通信波长宽带全介电谷光子晶体的设计
DOI：
10.1016/j.optcom.2021.126847
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发表时间：
2021-02-12
影响因子：
2.4
通讯作者：
Yang, YiBiao
中科院分区：
文献类型：
--
作者：
Han, YuHui;Fei, HongMing;Yang, YiBiao
拓扑光子晶体（Topological Photonic Crystal，TPC）能有效抑制缺陷的后向散射，实现高前向透过率的单向传输，在集成光子芯片应用中具有广阔的应用前景。在不同的光子晶体中，基于量子谷霍尔效应（QVHE）的谷光子晶体（VPCs）可以利用现有的CMOS纳米加工技术，利用硅等传统的介质材料，在通信波段实现自旋相关的单向传输。因此，VPC最近引起了广泛的关注。通常，在光通信和信息处理中，大的工作带宽是优选的，其应当尽可能大。目前，VPC在电信波长处的最大工作带宽被限制在130 nm左右。在理论分析和数值模拟的基础上，提出了一种由全介质硅基三角形空气孔构成的三角晶格VPC，并将1550 nm处的工作带宽进一步扩展到229 nm。通过结合两个镜像反转的VPC，我们观察到的山谷？自旋锁定行为导致体VPC内的选择性净自旋流，以实现具有高达0.97的高前向透射率的单向透射。此外，入射光的强度分布在锯齿形的尖锐边缘处显示出可忽略的散射损失，并且？形波导，证实了散射免疫传播的实现。所设计的VPC不仅提供了扩展工作带宽的可能性，而且可以应用于集成光子学和信息处理中使用自旋相关输运的器件应用。
Topological photonic crystals (TPC) can effectively suppress the backscattering from defects and achieve unidirectional transmission with high forward transmittance, thus becoming a promising candidate in integrated photonic chip applications. Among different TPCs, the valley photonic crystals (VPCs) based on quantum valley Hall effect (QVHE) originating from valley-dependent spin-split bulk bands, can achieve spin-dependent unidirectional transmission at telecommunication wavelength with conventional dielectric material, such as silicon, which can be readily fabricated by current CMOS nanofabrication techniques. Therefore, VPCs recently attract broad attention. Generally, a large working bandwidth is preferred in optical communications and information processing, which should be as large as possible. Currently, the maximum working bandwidth of VPCs at telecommunication wavelength is limited to about 130 nm. Based on theoretical analysis and numerical simulation, a triangular lattice VPC composed of all-dielectric silicon-based triangular air holes is proposed, and the working bandwidth at 1550 nm is further extended to 229 nm. By combining two mirror-inversed VPCs, we observe the valley?spin locking behavior results in selective net spin flow inside bulk VPCs to achieve unidirectional transmission with a high forward transmittance up to 0.97. Moreover, the intensity distributions of the incident light show neglectable scattering loss at the sharp edge of the zigzag and ?????? shape waveguides, confirming the achievement of scattering immune propagation. The designed VPCs not only offer a possibility to expand the working bandwidth, but also can be applied to device applications in integrated photonics and information processing using spin-dependent transportation.