Zhao Bo, Lin Lin, Lawrence Mark
Department of Electrical & Systems Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States.
Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States.
Nano Lett. 2025 Feb 5;25(5):1862-1869. doi: 10.1021/acs.nanolett.4c05260. Epub 2025 Jan 28.
Dielectric metasurfaces have emerged as an unprecedented platform for precise wavefront manipulation at subwavelength scales with nearly zero loss. When aiming at dynamic applications such as AR/VR and LiDAR, high-quality factor (high-Q) phase gradient metasurfaces have emerged as a way to boost weak light-material interactions in flat-optical components. However, resonant features are naturally tied to polarization, limiting devices to operating on a single polarization state, which reduces the efficiency and adaptability of wave-shaping. Here, we propose polarization-independent high-Q phase gradient metasurfaces, where two cross-polarized dipolar guided mode resonances (DGMRs) with similar Q around 300 are spectrally aligned while being spatially tuned. Our simulations demonstrate that, by adding less than 5% geometric perturbation, the metasurface can steer arbitrarily polarized beams to 31° with diffraction efficiency >70%. These devices show potential for advancing programmable polarization-independent wavefront shaping and unlocking ways to efficiently sculpt nonlinear frequency generation and mixing processes.
介电超表面已成为一个前所未有的平台，可在亚波长尺度上进行精确的波前操纵，且损耗几乎为零。当针对诸如AR/VR和激光雷达等动态应用时，高品质因数（高Q）相位梯度超表面已成为增强平面光学元件中微弱光与物质相互作用的一种方式。然而，谐振特性自然地与偏振相关联，这限制了器件只能在单一偏振态下工作，从而降低了波整形的效率和适应性。在此，我们提出了与偏振无关的高Q相位梯度超表面，其中两个具有相似Q值（约为300）的交叉偏振偶极子导模共振（DGMR）在光谱上对齐，同时在空间上进行调谐。我们的模拟表明，通过添加小于5%的几何微扰，该超表面可将任意偏振光束转向31°，衍射效率>70%。这些器件在推进可编程的与偏振无关的波前整形以及开启有效塑造非线性频率产生和混合过程的方法方面显示出潜力。
