AI 中文总结
研究在圆双折射等离子体结构中实现与基无关的几何相位调制，通过引入由空间旋转手性螺旋单元构成的超表面，利用圆双折射产生空间变化圆延迟，经理论分析和实验验证，建立了该几何相位积累的新方法。
AI 中文摘要
在超表面中，几何相位通常是在圆偏振照明下，通过空间旋转的线性双折射超原子来实现的。在此，我们证明了通过圆双折射可以实现完整的约2π几何相位调制，并在线性偏振激发下观察到。我们引入了一种由空间旋转的手性螺旋单元组成的等离子体超表面，设计用于产生空间变化的圆延迟。这产生了一个相当于闪耀光栅的几何相位斜坡，在动量空间中导致±1衍射级。使用泄漏辐射显微镜，我们直接分辨出这些级，并展示它们的强度如何取决于输入线性偏振，证实了相位的几何起源。我们使用旋转的庞加莱空间对该现象进行了理论分析，并通过直接测量斯托克斯参数证实了我们的结果。这些结果建立了一种在圆双折射等离子体超表面中与基无关的几何相位积累方法。
英文摘要
Geometric phase in metasurfaces is conventionally realized using spatially rotated linearly birefringent meta-atoms under circularly polarized illumination. Here we demonstrate that full $\sim2π$ geometric phase modulation can be achieved through circular birefringence and observed under linear polarization excitation. We introduce a plasmonic metasurface composed of spatially rotated chiral spiral unit cells designed to produce space-variant circular retardance. This generates a geometric phase ramp equivalent to a blazed grating, leading to $\pm1$ diffraction orders in momentum space. Using leakage radiation microscopy, we directly resolve these orders and show how their intensities depend upon the input linear polarization confirming the geometric origin of the phase. We theoretically analyze the phenomenon using a rotated Poincaré space and confirm our results by direct Stokes parameters measurement. These results establish basis-independent approach to geometric phase accumulation in circularly birefringent plasmonic metasurfaces.
