Abstract
We propose a planar THz hybrid bulk Dirac semimetal (BDS)-metal metamaterial which consists of a hybrid BDS-metal array on a dielectric layer and a back metallic mirror. The simulation results show that a spectral window that possesses high reflectance with no polarization conversion effect arises in the polarization conversion pass band due to the existence of the BDS rods. Interestingly, though the proposed structure possesses no symmetry property, the effects are nearly the same for x- and y-polarization incidences. We analyze the electric field distributions at the breaking frequency and attribute the phenomena to plasmonic analogue of electromagnetically induced reflectance (EIR-like) effect for x-polarization incidence and direct back scattering for y-polarization incidence. The dependence of the breaking window on the BDS rod length shows that, for both x- and y-polarization incidences, the breaking characteristic is mainly determined by the dipole resonance on the BDS rod. Moreover, the breaking window can be independently and dynamically manipulated by changing the Fermi energy of the BDS rods. Our results may provide potential applications in designing new polarization control devices.
Highlights
Metamaterial, the artificially constructed structure, has been widely studied in the function of negative refraction index [1]–[3], perfect lens [4] and invisible cloaks [5]
We numerically investigate the polarization insensitive tunable breaking window in the polarization conversion pass band of a planar terahertz hybrid bulk Dirac semimetal (BDS)-metal metamaterial, by using the finite-difference time-domain (FDTD) method
We first calculated the scattering matrix coefficients of the whole structure, the sole gold rectangle and the sole BDS rod respectively. For both x- and y-polarization incidences, a spectral window that possesses high reflectance with no polarization conversion effect arises in the broad polarization conversion pass band due to the existence of BDS rod
Summary
Metamaterial, the artificially constructed structure, has been widely studied in the function of negative refraction index [1]–[3], perfect lens [4] and invisible cloaks [5]. The EIT-like effect has been introduced to a chiral metamaterial [22] to break the asymmetric transmission in a narrow pass band, which provides a new way in manipulation light propagation. We numerically investigate the polarization insensitive tunable breaking window in the polarization conversion pass band of a planar terahertz hybrid BDS-metal metamaterial, by using the finite-difference time-domain (FDTD) method. We investigate the polarization conversion effect for different Fermi energies of BDS rod, the breaking window can be manipulated by changing the Fermi energy of the BDS rods without changing the background polarization conversion pass band. Different from our former work [22] that applies EIT-like effect to break the optical chirality of asymmetric transmission, this work is oriented for THz reflection polarization conversion with the breaking window being controlled at will, which opens a new route in controlling THz waves
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