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Wavefront control is the fundamental requirement in optical informatics. Planar optics have drawn intensive attention due to the merits of compactness and light weight. However, it remains a challenge to freely manipulate the dispersion, hindering practical applications, especially in imaging. Here, we propose the concept of frequency-synthesized phase engineering to solve this problem. A phasefront-frequency matrix is properly designed to encode different spatial phases to separate frequencies, thus makes arbitrary dispersion tailoring and even frequency-separated functionalization possible. The periodically rotated director endows cholesteric liquid crystal with a spin and frequency selective reflection. Moreover, via presetting the local initial orientation of liquid crystal, geometric phase is encoded to the reflected light. We verify the proposed strategy by cascading the chiral anisotropic optical media of specifically designed helical pitches and initial director orientations. By this means, planar lenses with RGB achromatic, enhanced chromatic aberration and color routing properties are demonstrated. Inch-sized and high-efficient lenses are fabricated with low crosstalk among colors. It releases the freedom of dispersion control of planar optics, and even enables frequency decoupled phase modulations. This work brings new insights to functional planar optics and may upgrade the performance of existing optical apparatuses. [ABSTRACT FROM AUTHOR]

Reciprocal spin‐orbit coupling (SOC) via geometric phase with flat optics provides a promising platform for shaping and controlling paraxial structured light. Current devices, from the pioneering q‐plates to the recent J‐plates, provide only spin‐dependent wavefront modulation without amplitude control. However, achieving control over all the spatial dimensions of paraxial SOC states requires spin‐dependent control of corresponding complex amplitude, which remains challenging for flat optics. Here, to address this issue, a new type of flat‐optics elements termed structured geometric phase gratings is presented, that is capable of conjugated complex‐amplitude control for orthogonal input circular polarizations. By using a microstructured liquid crystal photoalignment technique, a series of flat‐optics elements is engineered and their excellent precision in arbitrary SOC control is shown. This principle unlocks the full‐field control of paraxial structured light via flat optics, providing a promising way to develop an information exchange and processing units for general photonic SOC states, as well as extra‐/intracavity mode convertors for high‐precision laser beam shaping. [ABSTRACT FROM AUTHOR]

Multidimensional and large‐scale parallel manipulation of light, especially on‐demand tailoring of the working frequency and spatial phase front, is highly pursued in modern optics. Here, broadband tunable planar optics is demonstrated by electrically driving the nanohelix of photopatterned heliconical cholesterics. By preprogramming the initial orientation of the helixes using a dynamic‐mask photoalignment technique, spatial geometric phases can be arbitrarily encoded to the reflected light in a reconfigurable way. Due to the reversible electrically variant pitch of the heliconical superstructures, the reflective Bragg band can be precisely selected in the range from 380 to 1550 nm. In addition to wavelength selection and geometric phase modulation, spatial amplitude modulation and spin reversion can be further expected. This may offer a platform for full‐dimensional manipulation of light, including wavelength/frequency, phase, amplitude, time, and spin, thus upgrading optical information processing techniques. [ABSTRACT FROM AUTHOR]

Orbital angular momentum (OAM) provides a novel degree of freedom for light, deeply inspiring versatile light‐matter interactions and large‐density multiplexing computing. Recently, multimode and multichannel control of OAM beams have aroused extensive curiosity, whereas their flexible engineering in 3D space still remains challenging. Here, a new type of liquid‐crystal geometric phase optical elements is demonstrated to achieve on‐demand 3D tailoring of OAM beams. Via integrating binary and continuous phase patterns into photo‐aligned liquid crystals, customized 3D lattices of identical or propagation‐variant OAM beams are generated in an electrically tunable broadband manner. By altering the incident spin, these volumetric OAM beams can be switched among different states on the higher‐order Poincaré sphere. This work demonstrates a practical approach toward efficient OAM harnessing with large channel capacity and high spatial mode diversity, holding great potential for 3D optical manipulation, recording, and microscopy. [ABSTRACT FROM AUTHOR]

As a well‐recognized technology for optical data encoding and extracting, holography has faced an ever‐growing pursuit in the miniaturization, multifunctionality, and tunability for today's abundant information. Despite infusive achievements in metahologram, simultaneous realization of dynamic tunability and high‐dimensional multiplexing is critical yet lagging behind, which becomes one bottleneck for this emerging frontier. Here, an innovative solution is proposed by integrating the limited penetration depth of light in chiral liquid crystals and their intrinsic stimuli‐responsive characteristics. Based on a photoactive chiral dopant and the asymmetric photopatterning boundary confined self‐organization, light‐activated spectrally tunable, polarization‐ and direction‐dependent holograms are created simultaneously. As a promising example for information technology, an encrypted signal light is demonstrated, where the wavelength, propagation direction, helicity of light, and reaction duration serve as customized keys for information decryption. This work extends the construction of soft hierarchical superstructures and offers a satisfactory and open‐ended scheme for the intelligent holography, inspiring advanced display, security, and communication. [ABSTRACT FROM AUTHOR]

Airy beam and Airy vortex beam with intriguing characteristics have been extensively studied in linear optics, while their dynamic nonlinear conversion has rarely been explored and remains challenging. Here, through the collaboration of binary mask engineered nonlinear photonic crystal and space‐variant liquid‐crystal geometric phase element, second‐harmonic Airy beam and Airy vortex beam can be generated in a switchable manner. Electrical‐controlled loading of orbital angular momentum (OAM) into fundamental wave unlocks the flexibility of nonlinear process, which is well investigated in theory and further verified by experiment. Wavelength transformation, OAM conversion, and propagation trajectory inflection are realized simultaneously. This offers a convenient and universal strategy for dynamic nonlinear generation and shows great potentials in optical manipulation and information processing. [ABSTRACT FROM AUTHOR]

Featuring a nontrivial coupling between the orbital angular momentum of light and spatially inhomogeneous polarization, hybrid-order Poincaré sphere (HyOPS) beams have recently triggered numerous curiosities, especially in classical and quantum informatics. Despite much effort devoted to creating single HyOPS beam, it is still a formidable challenge to simultaneously harness multichannel and diverse HyOPS beams in a simple and efficient manner. Here, we propose a digitalized geometric phase optical element via photo-induced liquid crystal microstructures and demonstrate flexible and spin-controlled massive channels of HyOPS beams. By tuning the incident polarization, any state on up to 24 diverse HyOPSs is simultaneously mapped from common Poincaré sphere in high efficiency and good energy uniformity. All experimental results match well with the theoretical predictions of such a planar multifunctional device. This adds an extra spatial degree of freedom to advanced light tailoring and may facilitate parallel optical trapping, high-capacity communication, and high-dimensional quantum entanglement. [ABSTRACT FROM AUTHOR]

Terahertz (THz) band is expected to satisfy the ever‐increasing demand for high‐capacity wireless data transfer. Multifunctional photonic devices with compactness and low loss are highly pursued for future THz communications. Here, a strategy for planar THz photonics is proposed that enables free wavefront manipulation with submillimeter thin liquid crystal polymer (LCP) films. Such elements work on the spatial geometric phase modulation, which is accomplished by preprogramming the axis orientations of LCP. The LCP monomers follow the guidance of local photoalignment agent and are further polymerized under UV exposure at the existence of a doped photo‐initializer. Thanks to the high resolution and excellent flexibility of the photopatterning technique, THz elements with versatile functions can be realized. As examples, waveplates, polarization gratings, and lenses, which are suitable for the polarization control, beam deflecting, focusing, or collimating, are demonstrated. Due to the intrinsic flexibility of LCP films, an f‐tunable lens enabled by mechanically induced deformation is exhibited. Specific mode generators for vortices and Bessel beams are also presented, which can function as separate channels for the mode division multiplexing in THz communications. This work provides a robust platform for fabricating integrated, low‐loss, and tunable THz elements suitable for the advanced THz apparatuses. [ABSTRACT FROM AUTHOR]