Three-channel terahertz beam steering based on polarization multiplexed metasurfaces

Terahertz (THz) beam steering is of great significance for realizing high-speed communication, radar scanning, and information processing, but it is limited by the number of channels and strong crosstalk between different channels. In this work, we demonstrate a three-channel polarization multiplexed metasurface, enabling polarization-dependent and frequency-dependent multi-beam steering. The independent phase gradients are superimposed on a single-layer structure for three non-orthogonal polarization states, and we solved the supercell structure of the metasurface by Least Squares Approximation and Gradient Descent Algorithm to effectively suppress the crosstalk between non-orthogonal modes. The experimental results show that the deflection angles on different linear polarization states and frequencies can cover the angle range of 15°–50° in the broadband range of 0.3–0.5 THz, and the maximum crosstalk between channels is −27.84 dB at the center frequency of 0.4 THz. The proportion of beam energy correctly multiplexed by each channel reaches >80%. This non-orthogonal polarization multiplexing mechanism is of great value for THz metasurface multi-channel wavefront manipulation.