A dual-mode LiDAR system enabled by mechanically tunable hybrid cascaded metasurfaces.

Light detection and ranging (LiDAR) is widely used for active three-dimensional (3D) perception. Beam scanning LiDAR provides high accuracy and long detection range with limited detection efficiency, while flash LiDAR can achieve high-efficiency detection through the snapshot approach at the expense of reduced accuracy and range. With the synergy of these distinct detection approaches, we develop a miniaturized dual-mode, reconfigurable beam forming device by cascading Pancharatnam-Berry phase and propagation phase metasurfaces, integrated with a micro-actuator. By modulating incident light polarization, we can switch the output beam of the device between the beam array scanning mode and flash illuminating mode. In the scanning mode, the device demonstrates a continuously tunable angular resolution and a ± 35° field of view (FoV) through driving the micro-actuator to achieve the lateral translation of ±100 μm. In the flash mode, uniform illumination across the entire FoV is achieved. As a proof of concept, we propose an adaptive 3D reconstruction scheme that leverages the device's capability to switch operation modes and adjust detection resolution. Together, the proposed device and the detection scheme constitute a dual-mode LiDAR system, demonstrating high adaptability to diverse environments and catalyze the applications of more efficient and compact 3D detection systems.