Fig. 1. (a) Arbitrary polarization rotation and wavefront control capability of the device, such as beam deflection, focusing and vortex generation with different polarization rotation angles. (b) The array structure of a meta-device consisting of "super-units", where the chiral meta-atoms are rotated with different angles. (c) The composition of a "super-unit", where the red and blue parts respectively represent two different chiral meta-atoms (enantiomer A and enantiomer B, Ent A and Ent B). (d) The geometric parameters of the chiral meta-atoms, which are applicable to both Ent A and Ent B.

Fig. 2. (a, b) Circularly polarized transmission coefficients of the chiral enantiomers. (c) The transmission component t_RL of the meta-atoms with different rotation angles. (d) The transmission amplitude and phase of chiral meta-atoms with different rotation angles at the operating frequency of 1 THz. (e) The localized electric field excited by LCP and RCP waves of meta-atoms with different rotation angles.

Fig. 3. (a) Scanning electron microscopy (SEM) images of the chiral metasurface sample, the scale bar is 200 μm. (b) Schematic diagram of the polarization resolved terahertz time-domain spectroscopy system. (c, d) Measured results of the circularly polarized transmission spectra for two chiral metasurfaces.

Fig. 4. (a–c) Simulation results of the transmission circular dichroism for three types of super-units. (d–f) Local electric field excited by circularly polarized waves at 1 THz for three types of super-units. (g–i) Super-units with different rotation angles and the simulation results of their optical rotation function (β= 0°, 45°, and 90°).

Fig. 5. (a) Simulated linearly polarized transmission spectra of the super-unit arrays (β=90°). (b) Example for generating relative phase between super-units (with common rotation angle β₁=0, 45, 90°). (c) Design of the metasurface phase profile for beam focusing. (d) Simulation results of the focused beam in longitudinal cross-section (xoz plane). (e, f) Simulation results of the focused beam in transverse cross-section (xoy plane). (g) Localized SEM images of the racemic dielectric metasurface. (h, i) Experimental results of focused beam in transverse cross-section. (j) Experimental optical path for measuring focused terahertz beam.