Weyl points, which are the degenerate points in three-dimensional momentum space, have been widely studied in the photonic system, and show some intriguing phenomena such as topologically protected surface states and chiral anomalies. Type-I Weyl systems possess a complete bandgap, and topologically protected surface states can be excited without disturbing the bulk states. In this work, we investigate the influence of the sign of coupling coefficient on the topological property of the system and find that type-I Weyl points can be realized by introducing a negative coupling between the stacking layers of the designed photonic crystal. We propose a new strategy to construct a type-I Weyl system by stacking the hexagonal photonic lattice. Different from the topological nontrivial photonic system with a positive coefficient, the negative couplings in the photonic system are realized by adding another resonating site between stacking layers. We theoretically demonstrate that the effective coupling between the resonating sites in adjacent layers sign-flips through the judicious design of the nearest coupling strength and eigenfrequency of the additional sites. The surface states at opposite boundaries of the proposed system have opposite group velocities, which is the feature of type-I Weyl points. Our study provides a new method of exploring topologically protected photonic systems and developing possible topological devices.

韦尔点是三维动量空间中的简并点，已经在光子系统中得到了广泛的研究，并表现出一些有趣的现象，例如受拓扑保护的表面态和手性异常。I型Weyl系统具有完全的带隙，并且可以激发受拓扑保护的表面态，而不会干扰整体态。在这项工作中，我们研究了耦合系数的符号对系统拓扑特性的影响，发现可以通过在设计的光子晶体的堆叠层之间引入负耦合来实现I型Weyl点。我们提出了一种通过堆叠六边形光子晶格来构建I型Weyl系统的新策略。与具有正系数的拓扑非平凡光子系统不同，光子系统中的负耦合是通过在堆叠层之间添加另一个谐振点来实现的。我们从理论上证明，通过对附加位置的最近耦合强度和本征频率进行明智的设计，相邻层中的共振位置之间的有效耦合会发生翻转。所提出系统的相对边界处的表面状态具有相反的基团速度，这是I型Weyl点的特征。我们的研究提供了一种探索受拓扑保护的光子系统并开发可能的拓扑设备的新方法。我们从理论上证明，通过对附加位置的最近耦合强度和本征频率进行明智的设计，相邻层中的共振位置之间的有效耦合会发生翻转。所提出系统的相对边界处的表面状态具有相反的基团速度，这是I型Weyl点的特征。我们的研究提供了一种探索受拓扑保护的光子系统并开发可能的拓扑设备的新方法。我们从理论上证明，通过对附加位置的最近耦合强度和本征频率进行明智的设计，相邻层中的共振位置之间的有效耦合会发生翻转。所提出系统的相对边界处的表面状态具有相反的基团速度，这是I型Weyl点的特征。我们的研究提供了一种探索受拓扑保护的光子系统并开发可能的拓扑设备的新方法。