Terahertz microstructure for artificial birefringence and its applications

Our recent research work on artificial birefringence and broadband polarization converter in terahertz (THz) functional devices was reviewed in this paper, we proposed the subwavelength dielectric gradient grating structure with artificial high birefringence, broadband and low dispersion, and the dielectric metasurface with line-square compound lattice which can realize polarization dependent EIT effect with a large artificial birefringence effect. On the basis, we presented a compound metasurface and a coupled dielectric-metal grating for broadband THz wave polarization conversion and asymmetric transmission. Moreover, we introduced two-dimensional materials into THz polarization devices, and proposed a switchable quarter-wave plate based on graphene grating and a carbon nanotube attached subwavelength grating for broadband THz polarization conversion and dispersion control. This work has greatly promoted the development and practical application of THz polarization devices.