Theoretical Design Of Eight-Band Linear-To-Circular Converter In Reflection And Transmission Modes Based On Self-Complementary Metasurfaces

Multiband linear-to-circular (LTC) metamaterial converters have promising applications in modern optical system. However, it is challenging to design a converter with conversion bands of more than four and the axial ratio of less than 3 dB due to the coupling interaction of different resonant structures in a unit cell. In this article, we demonstrate a broad class of self-complementary THz infinite thin metasurfaces composed of supercells of fractal metal rectangular patches and holes dimers of spanning 1 THz octave in bandwidth, while still being highly efficient. The advantages of this converter are as follows. The device is theoretically nonthickness; the LTC polarization conversion can be achieved in both the reflected and transmitted fields; the phase difference between two orthogonal linear polarization components is theoretically 90 degrees in any frequency. Therefore, an eight-band LTC converter is achieved in reflection and transmission modes. This new nonthickness multiband device will demonstrate a major advance toward an LTC synthetic metasurface in the THz band.