Transmission characteristics of the aperture-coupled rectangular resonators based on metal-insulator-metal waveguides

By using finite-difference-time-domain (FDTD) methods, transmission characteristics and field distribution profile of the aperture-coupled rectangular resonators are investigated in metal-insulator-metal (MIM) waveguide system. Simulation results indicate the aperture affects resonant modes of the rectangular cavity in different manner when the aperture is shifting along the rectangular cavity. Moreover, resonant modes can be selectively suppressed when the aperture locates at nodes of the magnetic field. Consequently, different transmission spectra and dip-wavelength can be obtained even with the same resonator length, which provides an additional degree to tailor the system response in the nanoscale. In addition, flexible resonance wavelength ratio and tunable free spectral range (FSR) can be obtained compared with conventional Fabry-Perot filter whose resonance wavelength ratio is approximately equal to 1:1/2:1/3 due to the limitation by the Fabry-Perot resonance.