Spin-Decoupled Transflective Spatial Light Modulations Enabled by a Piecewise-Twisted Anisotropic Monolayer.

Wavefront control lies at the heart of modern optics. Metasurfaces with specifically tailored resonators can encode different phases to two orthogonal polarization components, but suffer from wavelength-dependent efficiency, sophisticated fabrication, and limited size. Liquid crystals, another excellent candidate for planar optics, are restricted to spin-coupled conjugated phase modulations. Planar optics with spin-decoupled functions is expected to release the multifunctionality of modern optics. Here, a spin-decoupled transflective spatial light modulator is presented with a piecewise-twisted anisotropic monolayer. The phases of reflected and transmitted light can be independently customized by preprogramming the initial orientations of the periodic helix and mirror-symmetric dual-twist configuration, respectively. A transflective orbital angular momentum encoder and decoder is demonstrated, which is simultaneously compatible with different multiplexing techniques. This work releases the multifunctionality of advanced planar optics and may upgrade existing devices in optical informatics.

Pancharatnam-Berry phase reversal via opposite-chirality-coexisted superstructures.

Recently discovered reflective Pancharatnam-Berry phase (PB phase) from chiral anisotropic media (e.g., cholesteric liquid crystal, CLC) has aroused great interest in the emerging frontier of planar optics. However, the single chirality of common CLCs results in the intrinsic limitation of the same spin-selective PB phase manipulation, which means the reversal of the input spin cannot realize the conjugated PB phase. In this work, an innovative scheme based on opposite-chirality-coexisted superstructures is proposed to simultaneously modulate orthogonal circular polarization and get PB phase reversal. Through refilling CLC into a washed-out polymer network with opposite chirality and delicate photo-patterned structures, reflective optical vortex (OV) with opposite topological charges and vector beams with conjugated spiral PB phases are efficiently generated depending on the incident polarization. Furthermore, OV holograms are encoded to reconstruct polarization-selective OV arrays, indicating the strong capability of such opposite-chirality-coexisted anisotropic media. This work provides a new compact platform for planar optics, and sheds light on the architectures and functionalities of chiral superstructures.