Tunable band-pass plasmonic waveguide-filter in the near infrared region

A tunable multi-channel band-pass plasmonic filter in the near-infrared range is investigated using the finite element numerical method (FEM). The structure of the proposed waveguide filter consists of several dielectric slots sandwiched between two metal layers. The slots are filled with air and silica. Numerical analysis and simulation demonstrate that the number of bandpass channels, amplitude, intensity, and bandwidth can be adjusted by changing the geometrical parameters such as material, length of each slot, width, and number of intermediate slots in the filter. The proposed filter was studied in the wavelength range of 1–4 μm, exhibiting 2 to 5 transmission peaks with varying transmission powers. Given that the incident wavelength in this article is larger than the dimensions of the waveguide and slot, this structure can focus the light within a sub-wavelength scale. The proposed structure is expected to be used as an essential component of photonics devices due to its ability to confine light in the sub-wavelength region, simple fabrication, and multi-channel operation.