Spiral metasurface enables tunable directional edge enhancement

Abstract: Tunable directional edge enhancement facilitates the acquisition of distinct morphological features from objects, a capability that plays a vital role in enhancing the reliability and safety of autonomous driving systems. However, building a simple, miniature, and switchable directional edge enhancement system remains an urgent challenge. To address this, we propose a compact spiral metasurface capable of achieving tunable vertical and horizontal edge enhancement imaging without requiring a conventional 4f system, relying instead on a single integrated device. This functionality is realized by engineering the metasurface's spiral phase profile and its polarization-dependent response, where the edge enhancement direction is controlled by varying the incident beam's polarization, enabling switching between vertical and horizontal enhancement modes. Simulations demonstrate the metasurface's capability for switchable edge detection of lane markings and barrier contours. Broadband operation is also confirmed through simulation results. Owing to its compactness, switchable functionality, and broadband performance, the proposed spiral metasurface shows significant potential for applications in optical analog computing and autonomous driving.