Terahertz dichroic device withy multi-functionality, multi-band operation and multi-dimensional tunability

Most existing dichroic metasurfaces have limitations such as single operating band, single functionality, fixed dichroic performance or only adjustable in a single dimension, as well as complex structure. Here, we propose a terahertz dichroic device based on patterned graphene layer and gold layer to address these limitations. By utilizing the anisotropy endowed by the patterned graphene layer and the gold layer, the proposed device can achieve both dual-band circular dichroism (CD) and linear dichroism (LD), with maximum CD values of 0.866 at 1.09 THz and −0.614 at 1.76 THz, and maximum LD values of 0.779 at 0.51 THz and −0.633 at 0.76 THz. Meanwhile, the dichroism of the device can be regulated through multiple dimensions, i.e., the rotation angle of the top patterned graphene layer, the Fermi level of graphene and the incident angle. The proposed dichroic device offers multi-functionality, multi-band operation and multi-dimensional adjustability with a relatively simple structure, and is expected to be widely used in the fields of terahertz imaging, polarization detection, optical sensing and biological spectroscopy.