▎ 摘　　要

Terahertz (THz) frequency coders are indispensable components of broadband wireless communication systems of the future. However, the coding of THz wave at multiple frequencies is still a challenge. In this work, a 3 bit THz coder based on a graphene composite metasurface is proposed and simulated using a full-wave electromagnetic simulation software. The unit cell of the device consists of three graphene-embedded split-ring-resonators (SRRs), i.e., SRR1, SRR2, and SRR3. The device has three transmission peaks modulated by external voltages of V1, V2, and V3. The central frequency of the peak generated by SRR1 locates at 0.864 THz and its maximum modulation depth is 79.6%. The second peak generated by SRR2 locates at 1.161 THz and has a maximum modulation depth of 87%. The third peak at 1.541 THz is produced by SRR3 and has a maximum modulation depth of 85.3%. More importantly, the device can be used as a 3 bit coder, and the codes of 111, 110, 101, 011, 100, 010, 001, and 000 are successfully realized by controlling the voltages of V1, V2 and V3. The proposed device has potential applications in next-generation broadband wireless communications. (c) 2023 Optica Publishing Group