All-optical plasmonic switches based on Fano resonance in an X-shaped resonator coupled to parallel stubs for telecommunication applications

In this paper, all-optical plasmonic switches based on metal-insulator-metal (MIM) waveguide configurations are proposed. In these structures, a Kerr-type nonlinear material and Fano resonance are used to achieve all-optical switching. Firstly, it is shown that adding two stubs to a MIM waveguide creates a Fano resonance which can be used for switching applications (the first switch) and finally, it is shown that adding a cross-shaped resonator between the identical stubs can improve the switching performance (the second switch). In this work, the finite element method (FEM) is employed to numerically simulate the proposed structures. To validate the FEM simulation results, they are superimposed on the results obtained from the finite difference time domain (FDTD) method, for which a very good agreement is observed. According to our calculations, by applying an optical pump, while the transmission value for the first proposed switch varies from 0.53 to 0.03, this value changes from 0.60 to 0.02 for the second switch. The proposed all-optical switches have various advantages such as working at tele-communication optical wavelengths, having a compact size (390 nm x 675 nm), needing a lower pump intensity (which is approximately equal to 145 mW/mu m2 for both switches), and a simple designing mechanism.