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 $\Omega$ 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.

拓扑光子晶体（TPC）可以有效地抑制缺陷向后散射，并以高正向透射率实现单向传输，因此成为集成光子芯片应用中的有希望的候选者。在不同的TPC中，基于量子谷霍尔效应（QVHE）的谷光子晶体（VPC）源自与谷相关的自旋分裂体能带，可以利用常规介电材料（如硅）在电信波长下实现与自旋相关的单向传输。可以通过当前的CMOS纳米制造技术轻松制造。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优选较大的工作带宽，该带宽应尽可能大。目前，VPC在电信波长下的最大工作带宽被限制为约130 nm。在理论分析和数值模拟的基础上，提出了由全介电硅基三角气孔组成的三角晶格VPC，并将1550 nm处的工作带宽进一步扩展至229 nm。通过组合两个镜像反向的VPC，我们观察到谷子-自旋锁定行为导致散装VPC内部选择性的自旋流，从而实现单向传输，并具有高达0.97的高前向透射率。此外，入射光的强度分布在锯齿形和锯齿形的锐边处的散射损耗可忽略不计。提出了一种由全介电硅基三角气孔组成的三角晶格VPC，并将1550 nm的工作带宽进一步扩展至229 nm。通过组合两个镜像反向的VPC，我们观察到谷子-自旋锁定行为导致散装VPC内部选择性的自旋流，从而实现单向传输，并具有高达0.97的高前向透射率。此外，入射光的强度分布在锯齿形和锯齿形的锐边处的散射损耗可忽略不计。提出了一种由全介电硅基三角气孔组成的三角晶格VPC，并将1550 nm的工作带宽进一步扩展至229 nm。通过组合两个镜像反向的VPC，我们观察到谷子-自旋锁定行为导致散装VPC内部选择性的自旋流，从而实现单向传输，并具有高达0.97的高前向透射率。此外，入射光的强度分布在锯齿形和锯齿形的锐边处的散射损耗可忽略不计。$\Omega$形波导，证实了散射免疫传播的实现。设计的VPC不仅提供了扩展工作带宽的可能性，而且还可以将其应用于自旋相关传输的集成光子学和信息处理中的设备应用。