Efficient Analysis of Plasmonic circuits using Differential Global Surface Impedance (DGSI) Model

Differential global surface impedance (DGSI) model, a rigorous approach, has been applied to the analysis of three dimensional plasmonic circuits. This model gives a global relation between the tangential electric field and the equivalent surface electric current on the boundary of an object. This approach helps one bring the unknowns to the boundary surface of an object and so avoid volumetric discretization. It also eliminates the need for equivalent surface magnetic current consideration. Therefore, there is no need to evaluate the rather complex integral operator related to this current. This will result in a great reduction in computation time and memory resources. On the other hand, due to small field variations along the longitudinal direction of each boundary segment, it is suggested to use the two dimensional DGSI matrix in the analysis of a three dimensional plasmonic circuit. This leads to a much simpler formulation of the DGSI model. Besides, our numerical results verify that this simplifying assumption will not greatly affect the accuracy of the analysis. Plasmonic waveguides with different thicknesses along with a line coupler have been analyzed. The results are verified with the results of a commercial software as well as global surface impedance (GSI) model previously presented in the literature.