Linear and Nonlinear Optical Field Manipulations with Multifunctional Chiral Coding Metasurfaces

Optical chirality, which describes the property of asymmetric light–matter interactions for different handedness of polarization, plays an important role in physical photonics, biochemical processes, and molecular recognition. Recently, asymmetric optical responses of chiral nanostructures provide a wide platform for arbitrary and artificial manipulation of optical chirality. Here, a design strategy is theoretically and experimentally introduced to realize a spin-selective coding metasurface in both linear and third harmonic regimes with giant chirality. Significant chiral transmission and wavefront control are realized by a chiral coding metasurface composed of amorphous silicon (a-Si) resonators with C₂ symmetry. The resonators and the enantiomers are encoded with different transmission amplitude and phase. The information channels are expanded to six-fold with simultaneous multi-foci focusing and multi-vortex generation operating in different polarization and linear/nonlinear channels. The nonlinear chiral high-contrast imaging is also achieved for spin-selective pattern information transmission. The study significantly expands the information capacity of coding metasurfaces, and can be readily applied in optical systems for information transmission in both linear and nonlinear regimes.