Leaky Fourier Metasurface Enables Diffraction‐Order Multiplexed Focus Steering

ABSTRACT Leaky metasurfaces offer a promising route to integrated wavefront control, yet their overall performance is constrained by the intrinsic limitations of constituent meta‐atoms. Here, we propose a leaky Fourier metasurface (LFM) based on sinusoidally modulated microstrip lines to circumvent the bandwidth and functionality limitations imposed by meta‐atom configurations. By replacing discrete meta‐atoms with deterministic, non‐resonant Fourier gratings, the LFM enables broadband, diffraction‐order‐multiplexed beam and focus steering. An analytical framework directly links the sinusoidal modulation parameters to the phase profile, eliminating the need for complex meta‐atom optimization. As proof of concept, we demonstrate both far‐field beam steering and near‐field focus steering across three distinct diffraction orders, with experimental results validating the design. This platform provides a scalable and versatile approach to multifunctional wavefront manipulation, with potential applications in communications, sensing, and radar systems.