A plasmonic filter including Metal-Insulator-Metal waveguides (MIM) with an elliptical ring resonator is proposed. Using the Finite Difference Time Domain (FDTD) method, we analyze the amount of transmittance in the structure. The results show the creation of five resonance modes with narrow FWHM and suitable transmittance at the resonance points of the spectrum. The resonance wavelength and transmittance at the resonance points are tuned by changing the device geometry. In this structure, preventing the transmittance of the spectrum creates a band-gap between the wavelengths 919 nm–1388 nm, which by changing the size of the structure, the band-gap width changes. This filter also cuts off the transmission of wavelengths greater than 1707 nm. By adding a rectangular ring resonator outside the elliptical ring resonator, the performance of the device was improved and the transmittance included very narrow resonance modes. Due to the number of resonance modes and their narrow FWHM, the introduced structures can be used as devices for filtering several wavelengths, which significantly reduces costs and enhances economic efficiency for the production of plasmonic band-pass filters. Also, this structure can be used as band-stop and cut-off filters. This multiplicity of functions makes it cost-effective to use the proposed device for making integrated optics devices.
