Non-Interleaved Shared-Aperture Full-Stokes Metalens via Prior-Knowledge-Driven Inverse Design

Characterization of electromagnetic wave polarization states is critical in various applications of materials, biomedical, and imaging. The emergence of metasurfaces opens up the possibility of implementing highly integrated full-Stokes imagers. Despite rapid development, prevailing schemes on metasurface-based full-Stokes imagers require interleaved or cascaded designs, inevitably resulting in performance deterioration, bulky size, and complicating the imaging procedure due to misalignment. To overcome these challenges, a non-interleaved shared-aperture full-Stokes metalens enabled by the prior-knowledge-driven inverse design methodology is proposed. The metalens can be directly deployed into imagers, performing high-accuracy diffraction-limited full-Stokes imaging without other ancillary components, breaking intrinsic constraints of efficiency and resolution in interleaved design. To demonstrate this, the metalens is integrated into the W-band passive imaging system, as an alternative solution, to perform polarimetric imaging, which reduces the reliance on the high cost and high complexity of the ortho-mode transducer and broadband correlator in traditional polarimetric radiometers. Furthermore, with the assistance of a 3D reconstruction method, the feasibility of multi-polarization information for contactless surface slope measurements is explored. This work may open new paradigms for the full-Stokes imager designing and broaden the applications of metasurface polarimetric imaging.