Polarization-Independent High-Q Phase Gradient Metasurfaces.

Abstract

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.