The Dirac-like dispersion in photonic systems makes it possible to mimic the dispersion of relativistic spin-1/2 particles, which led to the development of the concept of photonic topological insulators. Despite recent demonstrations of various topological photonic phases, the full potential offered by Dirac photonic systems, specifically their ability to emulate the spin degree of freedom—referred to as pseudo-spin—beyond topological boundary modes has remained underexplored. Here we demonstrate that photonic Dirac metasurfaces with smooth one-dimensional trapping gauge potentials serve as effective waveguides with modes carrying pseudo-spin. We show that spatially varying gauge potentials act unevenly on the two pseudo-spins due to their different field distributions, which enables control of guided modes by their spin, a property that is unattainable with conventional optical waveguides. Silicon nanophotonic metasurfaces are used to experimentally confirm the properties of these guided modes and reveal their distinct spin-dependent radiative character; modes of opposite pseudo-spin exhibit disparate radiative lifetimes and couple differently to incident light. The spin-dependent field distributions and radiative lifetimes of their guided modes indicate that photonic Dirac metasurfaces could be used for spin-multiplexing, controlling the characteristics of optical guided modes, and tuning light–matter interactions with photonic pseudo-spins.

光子系统中的类狄拉克色散使得模拟相对论自旋 1/2 粒子的色散成为可能，这导致了光子拓扑绝缘体概念的发展。尽管最近展示了各种拓扑光子相，但狄拉克光子系统所提供的全部潜力，特别是它们模拟超越拓扑边界模式的自旋自由度（称为赝自旋）的能力仍未得到充分探索。在这里，我们证明了具有平滑一维俘获规范势的光子狄拉克超表面可作为具有携带赝自旋模式的有效波导。我们表明，由于场分布不同，空间变化的规范电位对两个赝自旋的作用不均匀，这使得能够通过自旋控制导模，这是传统光波导无法实现的特性。硅纳米光子超表面用于通过实验确认这些导模的特性，并揭示其独特的自旋相关辐射特征；相反的赝自旋模式表现出不同的辐射寿命，并且与入射光的耦合不同。其导模的自旋相关场分布和辐射寿命表明，光子狄拉克超表面可用于自旋复用、控制光导模的特性以及通过光子赝自旋调节光与物质的相互作用。