Multiband reciprocal polarization insensitivity electromagnetically induced transparency in metasurfaces

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.