A nanoscale Bragg grating reflector based on the defect metal-insulator-metal (MIM) waveguide is developed and numerically simulated by using the finite element method (FEM). The MIM-based structure promises a highly tunable broad stop-band in transmission spectra. The narrow transmission window is shown to appear in the previous stop-band by changing the certain geometrical parameters. The central wavelengths can be controlled easily by altering the geographical parameters. The development of surface plasmon polarition (SPP) technology in metallic waveguide structures leads to more possibilities of controlling light at deep sub-wavelengths. Its attractive ability of breaking the diffraction limit contributes to the design of optical sensors.
In this paper, a metal–insulator–metal straight waveguide structure with quadrant ring resonators (QRRs) is theoretically presented. The transmission spectra at output ports are studied by the finite element method (FEM). The simulation results show great filtering effects at specific wavelengths. In order to unidirectionally control plasmonic flows at waveguide junctions, the original design has been expanded to T- and X-shaped waveguides with the QRRs. The results reveal that obvious Fano effects can be achieved in T-shaped systems.
Articles you may be interested in Low-power, ultrafast, and dynamic all-optical tunable plasmonic analog to electromagnetically induced transparency in two resonators side-coupled with a waveguide system Plasmon-induced transparency in metamaterials: Active near field coupling between bright superconducting and dark metallic mode resonatorsThe multi-wavelength tunable plasmonically induced transparency (PIT) phenomena in two-ring and three-ring systems at infrared range were theoretically and numerically investigated. In the two-ring system, changing the bias voltage of graphene ring or the separation between graphene rings would induce an off-to-on PIT optical response. An asymmetry factor has been introduced to explain the corresponding transmission spectra. In the three-ring system, by bringing in a new asymmetry factor, multiple new PIT windows would arise at the left or right side of the original PIT windows. Numerical simulation by finite element method was conducted to verify our designs. Those proposed structures hence have potential in ultra-compact graphene optoelectronic devices at the infrared range. V C 2015 AIP Publishing LLC. [http://dx.
We propose a plasmonic Bragg reflector (PBR) composed of a single-layer graphene-based silicon grating and numerically study its performance. An external voltage gating has been applied to graphene to tune its optical conductivity. It is demonstrated that SPP modes on graphene exhibit a stopband around the Bragg wavelengths. By introducing a nano-cavity into the PBR, a defect resonance mode is formed inside the stopband. We further design multi-defect PBR to adjust the characteristics of transmission spectrum. In addition, through patterning the PBR unit into multi-step structure, we lower the insertion loss and suppress the rippling in transmission spectra. The finite element method (FEM) has been utilized to perform the simulation work.
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