Spin-selective nonlinear imaging in real and Fourier space via chiral metasurfaces

Abstract

Nonlinear chiral metasurfaces represent a compelling platform for spin-selective light–matter interactions and multidimensional optical information processing. However, existing designs are typically restricted to single-parameter manipulation or rely on intricate supercell architectures, making simultaneous and independent control of multiple wavefront degrees of freedom challenging. Here, we present a streamlined design paradigm for nonlinear chiral metasurfaces, in which spin-selective and independent modulation of amplitude and phase can be achieved by adjusting merely two geometric parameters of a single chiral meta-atom. As a proof of concept, we implement a multifunctional metasurface by arranging spatially segregated enantiomeric structures, experimentally demonstrate spin-selective dual-channel nonlinear imaging in real and Fourier space under left- and right-circularly polarized fundamental excitation. Each polarization channel simultaneously generates a near-field grayscale image (real space) and its corresponding far-field holographic reconstruction (Fourier space). This work paves the way toward multifunctional, high-efficiency, and ultracompact nonlinear photonic devices.