Ultracompact double tunable two-channel plasmonic filter and 4-channel multi/demultiplexer design based on aperture-coupled plasmonic slot cavity

In this paper, theoretical analysis and numerical simulations are applied to propose an ultracompact double tunable two-channel plasmonic filter based on aperture coupled plasmonic slot cavity. By knowledge of the exact distribution of the electromagnetic field inside the slot cavity and selecting the appropriate position of the output aperture, the resonance modes of the cavity can be separated. Also, adding a stub in the position of the antinode of the standing wave of the second resonance mode changes the effective length of the third resonance mode. Therefore, by variation of the length of the cavity and the stub, the resonance modes of the filter can independently be tuned. According to the proposed double tunable two-channel plasmonic filter, an ultracompact 4-channel multi/demultiplexer is proposed. The two-dimensional finite difference time domain (2D-FDTD) method has been used to numerically analyze the proposed structures. Our results open a new way for construction of nanoplasmonic multi-wavelength multi/demultiplexers to be used in plasmonic integrated circuits.