The European Physical Journal Applied Physics (EPJ AP) an international journal devoted to the promotion of the recent progresses in all fields of applied physics

A reciprocity electromagnetically induced transparency (EIT) effect can be obtained in the complementary graphene metasurface structure. The EIT spectra can be obtained whether the excitation was input from a positive or reverse direction. The transmission of the structure which consisted of a graphene square (GS) and the graphene circle of hollowed air square (GCHAS) placed on the top and bottom of the polyimide layer was discussed. A wideband EIT window was found in the structure of GCHAS as bright mode and GS as dark mode by the finite integration time domain method. The EIT effect can be tuned by the chemical potential, the electron-phonon relaxation time of graphene, and the widths of GCHAS and GS, respectively. The polarization insensitive EIT effect can be obtained. The transmission mechanism is interpreted by giving the electric and magnetic field distributions at certain frequencies. The effective permittivity of the structure was calculated by method of inversion. These results can be applied for many areas, such as wideband wavelength slow-light devices, active plasmon switching and bidirectional devices.

A classical structure for a U-shaped metasurface exhibiting a wideband and large angle electromagnetically induced transparency (EIT) effect in the terahertz range is proposed. One horizontal and two vertical strips, which represent the bright and dark modes, respectively, are created for the U-shaped structure. The finite integration time domain (FITD) and equivalent circuit method are compared with the EIT result. The EIT effect is affected by the length of the vertical bar and by the distance from the vertical bar to the symmetry axis. The results show that the asymmetry of the main structure in the x and y axes makes it easier to achieve the EIT effect. In addition, by changing the incident angle, the EIT effect always exists until the angle of the incidental electromagnetic wave is 85 degrees. These results have many potential applications for terahertz filtering, large-angle switching and sensors.

The proposed graphene metasurface of composite structures of multi‐band and wide‐band transparency windows was investigated by the finite‐difference time‐domain method. The authors discussed a structure which consisted of graphene ribbons and TiO ₂ –SiO ₂ layer which was sandwiched in between two lithium fluoride dielectric slabs. An electromagnetically induced transparency (EIT) window could be found and tuned gently by the width of lithium fluoride dielectric slabs. Furthermore, an improved structure of air groove in the graphene ribbon was designed. The result showed that a wide‐band EIT window was obtained and tuned by the width and thickness of air groove. The existing research shows that the graphene ribbon is bright mode and LiF slabs are dark mode. These results can find potential applications for many areas such as multi‐band wavelength slow‐light devices, active plasmon switching, infrared invisibility and optical sensing.

A reciprocal electromagnetically induced transparency (EIT) effect is proposed in the complementary metasurface structure, which is composed of metal orthogonal strips beside a silicon substrate. The EIT effect of reciprocity is obtained whether the incident wave propagates from the positive (+z) or reverse (−z) direction. A multiband EIT window is also obtained in the structure of horizontal strip and substrate silicon as bright mode and vertical strip as dark mode by the finite difference time domain (FDTD) method. The transmission mechanism is interpreted by giving the current surface and electric field distributions at certain frequencies. A polarization insensitive EIT can be realized theoretically due to the structure is symmetrical in the x and y directions. The effective permittivity of the structure was calculated by the method of inversion to reveal the transmission spectra. These results can be applied in many areas, such as multiband slow-light devices, active sensing and bidirectional devices.