A linear polarization beam splitter operating in terahertz band is proposed and experimentally verified in this paper. The unit cell of beam splitter is composed of the top ``I'' type metal pattern, the middle dielectric layer, and the bottom metal layer. Each subarray structure of the device consists of four unit cells that rotate progressively at an angle of 45˚. The horizontal and vertical sub-arrays form the gradient metasurface of 4×4. The incident linear polarized terahertz wave is reflected by the device and divided into four beams with approximately equal power, while having different propagating directions in the 0.18-0.30 THz band. The proposed terahertz beam splitter has the advantages of small size, low cost, and easy processing, and it can be applied to terahertz stealth and terahertz imaging.
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