Dynamically reconfigurable graphene-vanadium dioxide metasurface with switchable polarization conversion, multiband absorption, and programmable scattering control.

This study demonstrates a dynamically reconfigurable, multifunctional graphene-vanadium dioxide (VO2) metasurface with switchable polarization conversion, multiple wideband and narrowband absorption, and exceptional monostatic and wideband bistatic radar cross-section (RCS) reduction capabilities. The proposed device exhibits scarcely observed switching proficiencies from a broadband linear-to-circular polarization converter (LTCPC) to a broadband linear-to-linear cross-polarization converter (LTLPC) with a high fractional bandwidth (FBW) by varying temperature as well as surface potential of graphene. The unit cell structure includes three parallel graphene patches oriented along the diagonal axis on a silicon dioxide (SiO2) substrate, with a vanadium dioxide (VO2) ground layer that enables a transmissive-reflective configuration in the insulating and metallic phases of VO2. In the metallic state of VO2, the device demonstrates LTCPC over the frequency range of 2.06-3.69 terahertz (THz), corresponding to a 56.69% FBW at a chemical potential (CP) of 0.8 eV, and LTLPC over 1.95-3.77 THz, yielding a 63.63% FBW at a CP of 1.2 eV. In addition, six absorption bands are observed across the frequency range of 1.72-10.32 THz. In the insulating phase, the device provides LTLPC over 1.62-2.88 THz, corresponding to a 56.0% FBW, along with dual-band absorption at 1.59 THz and 7.81 THz, exhibiting peak absorptivities of 89.58% and 95.61%, respectively. In the metallic phase, the metasurface offers excellent monostatic RCS reduction exceeding 20 dB, as well as broadband bistatic RCS reduction in both phases of VO2. The device maintains excellent incident-angle insensitivity up to 50° for LTCPC and 40° for LTLPC.