We propose the monolayer graphene with a periodic stack of the dielectric materials to achieve comb-like absorption enhancement. The number of absorption peaks corresponds to the stacked period number of two dielectric materials. The simulation and theoretical results illustrate that the appearance of multiple absorption peaks is attributed to the excitation of multiple waveguide modes confirmed by using the multiple waveguide theory. The perfect absorption peaks at any desired wavelength in the visible range can be tuned by carefully optimizing the structural parameters and the stacked period number of two dielectric materials.

A hybrid structure of graphene ribbons suspended on grooves of a periodic SiC grating is proposed. Magnetic polaritons in the SiC grating can couple with surface plasmons in graphene ribbons. The field distributions obtained from COMSOL simulation, in agreement with the prediction from a LC circuit model, strongly indicate that magnetic polaritons can be excited in the SiC grating. We find that the SiC grating cavity acts as a perfect reflector; plasmon standing waves can be established under a certain size of the SiC grating. These standing waves can be confirmed using a Fabry–Perot model. The Fermi energy of graphene, and height of the grating can control the plasmon standing waves. Moreover, we analyze how the strong coupling between localized magnetic polaritons in the SiC grating and surface plasmons in graphene ribbons leads to the Rabi splitting of the absorption peak and perfect absorption in the mid-infrared region using a coupled harmonic oscillator model. These findings may promote the development of optoelectronic devices based on hybrid structures and can pave the way for the hybridization of the two types of modes.

Local confinement of light is very important to the field of optics, and it is theoretically possible to achieve the perfect confinement for optical modes located in the continuous domain radiation state. Achieving perfect confinement is possible for bound states in the continuum(BIC), which localize waves that lie in the continuous spectrum of the radiative state and remain in a perfect localized state. In this letter, we propose a metasurface that consisted of arrays of silicon nano-ellipsoidal pairs and calculate its transmission spectra and energy bands. Based on an all-dielectric metasurface, a dielectric multilayer film is incorporated to improve the quality factor of the array composed of ellipsoidal table pairs by an order of magnitude. By breaking the symmetry of ellipsoidal table pairs, quasi-BIC resonance modes excited by electric quadrupole(EQ) and magnetic dipoles(MDs) are realized using asymmetric silicon nanoellipsoid surfaces, where the quasi-BIC modes have high Q-factors. In this paper, the relationship between the structural asymmetry of Fano resonance controlled by symmetry-protect BICs and the radiation Q-factor is analyzed and demonstrated theoretically. At the same time, we use quasi-BIC resonances in asymmetric silicon nano-ellipsoidal pairs of metasurfaces to achieve a huge Goos-Hänchen (GH) shift enhancement which exceeds the 3rd-order wavelength and a very large group index to achieve excellent slow-light effects. Our work is centered on the design of simulations for the BIC metasurface. Meanwhile, based on the simulation design results, we propose to advance the application of optical communication devices, BIC sensing, optical switches, and optical modulators.

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.