▎ 摘　　要

In this study, an all-optical plasmonic D flip-flop based on graphene is proposed. A graphene layer is sandwiched between two SnO2 layers for confinement and transmission of surface plasmon polaritons. A resonant ring is designed for approaching the constructive interferences for a wavelength of 12.9 mu m. Two output ports Q and Q ' receive the applied signal from inputs D and Clk. By adjusting the graphene chemical potential of 0.1 eV and 1 eV, the transmittance of the waveguides can be controlled. Concerning the structure's dimensions, a low loss of 0.34 dB/mu m for waveguides with a width of 50 nm allows the surface plasmon polaritons to transmit through the designed waveguides in response to a chemical potential of 1 eV. The area of the designed subwavelength flipflop is as small as 0.27 mu m2, more compact than the previous works. The cross-talk of -7.78 dB is another advantage of the presented structure that helps to close the waveguides. Compactness and low cross-talk are the essential parameters in designing optical circuits. Also, the contrast ratio of Q and Q ' is equal to 13.83 dB and 3.63 dB, respectively. The obtained results promise the designed flip-flop for use in optical circuits.