Broadband modeling surface plasmon polaritons in optically pumped and curved graphene structures with an improved leapfrog ADI-FDTD method

An improved one-step leapfrog alternating-direction-implicit finite-difference time-domain (ADI-FDTD) method is proposed to study surface plasmon polaritons (SPPs) in optically pumped and electrostatic applied curved graphene structures, with their intraband and interband surface conductivities modeled with the vector fitting technique. Such a method can quickly capture the broadband characteristics of SPPs propagating along monolayer, bilayer and trilayer graphene sheets of arbitrary shapes. Numerical stability and accuracy are validated through characterizing field distributions of the SPPs supported in the 180°-curved and spiral graphene sheet waveguides and higher computational efficiency are achieved in comparison with the conventional FDTD method.