multiple-channel plasmonic filter based on metal-insulator-metal waveguide and fractal theory

A multiple-channel plasmonic filter based on metal-insulator-metal waveguide and fractal theory is proposed. the sandwiched insulator layer is constructed by a series of dielectrics with different refractive indices by following the fractal theory for the first time, to the best of our knowledge. in the designed plasmonic filter with orthogonal defect states, the number of channels can be adjusted through the arrangement of the insulator layer and each channel can be independently controlled by changing the refractive indices of coupling dielectrics in the insulator layer. in particular, a filter with three transmission channels has been designed. the characteristics of the transmission spectrum are investigated by using the finite-difference time-domain method. numerical results indicate that this triple-channel plasmonic filter has high transmission efficiency greater than 0.51 and a narrow bandwidth less than 3.9 nm. consequently, the proposed structure is capable of implementing compact multiple-channel filters for many specific applications, such as integrated devices or subsystems.