Universal active nonlocal metasurface with ultimate wavefront shaping performance

In this work, we introduce an innovative and versatile design strategy that relies on asymmetric Gires-Tournois resonators to enable active full-phase modulation with nearly perfect efficiency. We investigated the complex frequency response of these resonators, identifying the necessary conditions for ideal phase/amplitude modulation response, where achieving unity reflection relies on specific zero-pole position in the complex plane. We explored various active metasurface materials, spanning from silicon to hetero-structured materials, enabling comprehensive phase modulation even with small refractive index changes on the order of 0.01. To address the strong nonlocal effect, we exploited our global statistical learning optimization to fine-tune the refractive index distribution. This optimization resulted in active wavefront shaping designs that surpass 90% in performance. This development holds significant promise for applications in advanced microscopy and LiDAR, pushing the boundaries of optical technology.