Fig. 1. Schematic diagram of dynamic function switching of THz waves via mode decoupling controlled by external physical field stimulus. When y- (or x-) polarized waves impinge vertically, the reflected waves undergo polarization conversion and produce independent phase shifts in the two modes, achieving different functions.

Fig. 2. (a) Schematic diagram of the unit structure and parameter annotation. (b) Equivalent structure diagram, (c) surface current distribution, and (d) corresponding S-mode field distribution of the unit in the insulating state at normal temperature. (e) Equivalent structure diagram, (f) surface current distribution, and (g) corresponding D-mode field distribution of the unit in the metallic state at high temperature.

Fig. 3. (a) Amplitude of reflected cross-polarization wave in S-mode at room temperature and (b) corresponding phase delay. (c) Amplitude of reflected cross-polarization wave in high-temperature D-mode and (d) corresponding phase delay.

Fig. 4. (a) Spectra of the reflected cross-polarized wave (top) and corresponding phase delay (bottom) for forward illuminated y-polarized light in S-mode. (b) Spectra of the reflected cross-polarized wave (top) and corresponding phase delay (bottom) for forward illuminated y-polarized light in D-mode. Amplitude–phase distribution of reflected cross-polarization at 340 GHz for the selected superatom in (c) S-mode and (d) D-mode.

Fig. 5. Simulation and experimental results of the reflected cross-polarized wave focusing off-axis with tunable focal length when y-polarized wave is vertically incident. (a) Simulation results of Ex distribution in xoz plane in S-mode. (b) Simulation results of Ex distribution in xoz plane in D-mode. (c)–(e) Experimental results of Ix distribution measured at sections A (L=15  mm), B (L=17  mm), and C (L=20  mm) in (a). (f)–(h) Experimental results of Ix distribution measured at sections D (L=11  mm), E (L=13  mm), and F (L=15  mm) in (b).

Fig. 6. Simulation and experimental results of the reflected cross-polarized wave focusing off-axis with large-angle focus deflection when y-polarized wave is vertically incident. (a) Simulation results of Ex distribution in xoz plane in S-mode. (b) Simulation results of Ex distribution in xoz plane in D-mode. (c)–(e) Experimental results of Ix distribution measured at sections A (L=11  mm), B (L=13  mm), and C (L=15  mm) in (a). (f)–(h) Experimental results of Ix distribution measured at sections D (L=11  mm), E (L=13  mm), and F (L=15  mm) in (b).

Fig. 7. (a) Image of a fabricated metasurface sample and (b) its partially enlarged view. (c) Schematic diagram of the experimental setup.