Switchable Abnormal THz Wave Reflector Based on Molybdenum Disulfide (MoS2)

Recently Controlling the electromagnetic wave, especially in terahertz range is highly demanded due to the development of practical devices and application systems. In this paper, we propose a scheme to design tunable abnormal reflection structure consisting of molybdenum disulfide (MoS
₂
) array on a grounded SiO
₂
and a gold layer beneath them to reflect the terahertz wave. In this structure, MoS
₂
can be controlled by intrinsic carrier density or voltage bias, to control the electromagnetic reflected beam at terahertz frequency. By adjusting the geometric dimensions of the MoS
₂
elements, the reflection phase can cover the range of 0-2π with linear phase shift, thus abrupt phase shifts can be introduced to design the reflected wavefront. Furthermore, the reflective phase gradient over the structure can be switched by controlling the intrinsic carrier density or voltage bias of the MoS
₂
, hence reflected beam directions can be switched dynamically. The proposed scheme will bring much freedom in the design of beam manipulation devices and may be applied to terahertz radiation control. Numerical simulations verify the Snell's law generalized at working frequency and far field scattering illustrate the abnormal reflection.