In this paper, we propose an all-solid-state, electrically tunable, and reflective terahertz phased array (TPA) based on a novel graphene metasurface. By designing and optimizing the key structural parameters of graphene antenna, the metasurface can achieve close to the continuous phase curves corresponding to different deflection angles and the accurate modulation of phase over 350° by the metasurface in THz spectrum. Based on the above two elements, the designed TPA can achieve a specific deflection angle or continuous scanning in the ultra-wide range of −79.11°∼79.11° almost without side lobe interference. A key feature of our design can maintain the beam steering function in the range of incident angle less than 20°. This method holds a promising potential for versatile utilization in integrated devices such as adjustable wavefront control.

Walking error has been problematic for pulsed LiDAR based on a single threshold comparator. Traditionally, walk error must be suppressed by some time discrimination methods with extremely complex electronic circuits and high costs. In this paper, we propose a compact and flexible method for reducing walk error and achieving distance-intensity imaging. A single threshold comparator and commercial time digital converter chip are designed to measure the laser pulse’s time of flight and pulse width. In order to obtain first-class measurement accuracy, we designed a specific pulse width correction method based on the Kalman filter to correct the laser recording time, significantly reducing the ranging walk error by echo intensity fluctuation. In addition, the pulse width obtained by our method, which is a recording of the laser intensity, is conducive to target identification. The experiment results verified plane point clouds of various targets obtained by the proposed method with a plane flatness less than 0.34. The novel contribution of the study is to provide a highly integrated and cost-effective solution for the realization of high-precision ranging and multi-dimensional detection by pulsed LiDAR. It is valuable for realizing multi-dimension, outstanding performance, and low-cost LiDAR.

Optical phased arrays (OPAs) are essential optical elements in applications that require the ability to manipulate the light-wavefront, such as beam focusing and light steering. To miniaturize the optical components, active metasurfaces, especially graphene metasurfaces, are used as competent alternatives. However, the metasurface cannot achieve strong resonance effect and phase control function in the mid-infrared region only relying on a single-layer graphene. Here we present a graphene-metal hybrid metasurface that can generate a specific phase or a continuous sweep in the range of a 275°-based single-layer graphene structure. A key feature of our design is that the phase adjustment mainly depends on the combination mechanism of resonance intensity and frequency modulation. An all-solid-state, electrically tunable, and reflective OPA is designed by applying the bias voltage to a different pixel metasurface. The simulation results show that the maximum deflection angle of the OPA can reach 42.716°, and the angular resolution can reach 0.62°. This design can be widely applied to mid-infrared imaging, optical sensing, and optical communication systems.

In this paper, we propose an all-solid-state, electrically tunable, and reflective graphene metasurface array that can generate a specific phase or continuous scanning between 0° and 352.5° in the terahertz band. By optimizing the structural parameters of the metasurface, the average reflectivity can reach 68.3%, and the maximum reflectivity variation range is only 30%. We also simulate the results that an electrically tunable terahertz phased array can be achieved by adjusting the Fermi levels of a monolayer graphene resonator. The maximum deflection of the reflected beam is 46.05°, and the resolution can be improved to 1.10°. It should be noted that the sidelobe energy only accounts for 1.06% of the main lobe energy, due to the slight change in reflectivity with the phase gradient.