Dynamically controlled asymmetric transmission of linearly polarized waves in VO₂-integrated Dirac semimetal metamaterials

We numerically demonstrated a novel chiral metamaterial to achieve broadband asymmetric transmission (AT) of linearly polarized electromagnetic waves in terahertz (THz) band. The proposed metamaterial unit cell exhibits no rotational symmetry with vanadium dioxide (VO_2) inclusion embedded between Dirac semimetals (DSMs) pattern. The resonant frequency of AT can be dynamically tunable by varying the Fermi energy (E_\rm F) of the DSMs. The insulator-to-metal phase transition of VO_2 enables the amplitude of the AT to be dynamically tailored. The transmission coefficient |T_yx| can be adjusted from 0.756 to nearly 0 by modifying the conductivity of VO_2. Meanwhile, the AT parameter intensity of linearly polarized incidence can be actively controlled from 0.55 to almost 0, leading to a switch for AT. When VO_2 is in its insulator state, the proposed device achieves broadband AT parameter greater than 0.5 from 1.21 THz to 1.80 THz with a bandwidth of 0.59 THz. When the incident wave propagates along the backward (-z) direction, the cross-polarized transmission |T_yx| reaches a peak value 0.756 at 1.32 THz, whereas the value of |T_xy| well below 0.157 in the concerned frequency. On the other hand, the co-polarized transmission |T_xx| and |T_yy| remained equal in the whole frequency range. This work provides a novel approach in developing broadband, tunable, as well as switchable AT electromagnetic devices.