Bandwidth-enhanced carpet cloak by using a phase-gradient metasurface with a multilayer unit cell in terahertz range

Abstract The metasurfaces can effectively manipulate the phase, polarization and amplitude of electromagnetic waves. The development of metasurfaces provides a new choice for designing ultra-thin and arbitrary-shaped carpet cloak devices. Here, we firstly use the classical Snell’s law to derive the generalized Snell’s reflection law for reflective cloak devices, and explores the working principle and design method of metasurface reflection cloak. A multi-layer metasurface structure is proposed to design a broadband terahertz wave carpet cloak device with well cloak effect in the wide frequency range from 0.67 THz to 0.85 THz. Based on Snell’s law, we innovatively cover the metasurface structural unit with a high refractive index dielectric layer to achieve a wide-angle response of the metasurface. Based on the full-wave simulation analysis of the finite integral method, the results show that the designed cloak still has a good cloak effect under the wide angle from 35°to 55°.