▎ 摘　　要

In this paper, we report on the design procedure for developing subwavelength graphene-based plasmonic waveguide, performing as a THz switch or an AND/OR logic gate. The propagation length of the surface plasmons (SPs), stimulated by a 6 THz TM polarized incident wave along this waveguide with a top graphene layer whose chemical potential is held at mu(C) = 300 meV (ON state) is more than 35 times larger than that in the waveguide with mu(C) = 0 eV (OFF state). Numerical results, obtained from full wave simulations using a finite element method, also show that the modulation depth density obtained for the straight plasmonic switching waveguide, whose length is just about 20% of the incident wavelength, is larger than those reported to date. Moreover, we also designed a logic AND gate composed of a straight waveguide, a Y-branch switch, and a logic OR gate composed of two face to face Y-branches, whose total lengths are similar to 37%, similar to 45%, and similar to 53% of the incident wavelength, respectively. Simulations show that the maximum ON/OFF ratios for these subwavelength plasmonic waveguides that occur between their '1 1' and '0 0' logical states are similar to 41.37, similar to 39.87, and similar to 40.76 dB, respectively. These numerical data also show that the modulation depth densities obtained for these devices are also greater than those reported to date. The proposed graphene-based plasmonic switches and gates offer potential building blocks for the future digital plasmonic circuits operating around 6 THz.