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.
A new strategy for simultaneous realization of dynamic and high‐dimensional multiplexed holography is proposed via light‐directed liquid‐crystalline chiral superstructures. Photoactive, bidirectional, polarization‐ and time‐dependent hologram is demonstrated. An encrypted signal light is further presented and decrypted into customized direction messages. This novel methodology integrates diverse multiplexing schemes into a single device, facilitating advanced display, security, and communication.
Novel options for multiplexing, such as orbital angular momentum (OAM), are sought to satisfy the explosive growth of information capacity. Consequently, spatial phase modulation with on‐demand ...tailoring of working bands is increasingly investigated. In this study, a polymer‐stabilized cholesteric liquid crystal is used to address this requirement. A varying DC voltage is applied, and the working band is increased over eightfold owing to the electric‐induced gradient pitch of the polymer network. Thus, the working band of an OAM processor is reversibly switched between narrowband and broadband states. An OAM‐multiplexing hologram is designed for parallel OAM encoding and decoding, enabling a wavelength‐division‐multiplexing compatible approach for in situ and non‐destructive OAM processing. The proposed design offers a promising solution for the on‐demand tailoring of working bands in liquid crystal planar optics and can promote advancements in massive information transmission and large‐capacity data processing.
Optical orbital angular momentum (OAM) processors with electrically tailored working bands are proposed based on polymer‐stabilized cholesteric liquid crystals. The photonic bandgap can be extended from 41 to 350 nm, enabling OAM‐based mode‐division multiplexing compatible with wavelength‐division multiplexing. This study is promising for large‐capacity optical communication and parallel information processing.
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.
A strategy for a spatial phase modulator with an electrically customizable working band is proposed via heliconical cholesterics. The photoalignment technique is adopted to realize arbitrary geometric phases. Electrically controllable heliconical superstructures enable working band selectivity over a broad range from near‐UV to near‐IR. This work enriches chiral superstructure manipulation and will upgrade present optical systems.
The microstructure, mechanical properties and stress corrosion cracking (SCC) of 7136 aluminum alloy under T6, T79 and T74 aging treatments were studied and the effects of microstructure on the ...mechanical properties and SCC were discussed. The results show that the ultimate tensile strength and yield strength of the aging 7136 alloys follow this sequence from high to low: T6>T79>pre-aging>T74. For 7136 Al alloy after T6 aging, the average diameter of the precipitates was (5.7±1.7) nm, and the diameter of 60.7% (number fraction) precipitates was 2–6 nm, leading to a good precipitation strengthening. The
K
IC
of T74-aging alloy is 38.2 MPa·m
1/2
, which is 26.1% more than that of T6-aging alloy and 17.5% more than that of T79-aging alloy. The improved fracture toughness in T74-aging alloy is mainly due to the reduction of the strength difference between intragranular and grain boundary. The SCC resistance of the aging 7136 alloys follows this sequence from high to low: T79 > T74 > T6. After T79 aging, the discontinuous grain boundary precipitates and narrow precipitate free zones were obtained in 7136 alloy, which was beneficial to SCC resistance.
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.
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. This work releases the multifunctionality of advanced planar optics and may upgrade existing devices in optical informatics.
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.
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.
Wavefront control lies in the heart of optics. Multi‐degree orthogonal manipulation of light, especially the on‐demand tailoring of the working band and spatial phase front, is expected to fully ...exhibit the superiority of photons as information carriers. Here, the recent progress on the customizable working band of liquid crystal planar optics enabled by helical structures is reviewed. Broadband transmissive devices with mirror‐symmetric helical structures, broadband reflective Bragg‐Berry phase elements based on cholesteric liquid crystals, transflective phase modulations of a piecewise twisted structure, and external field shifted bands of planar optics are summarized. In addition to the customization of the geometric phase and working band, manipulation of other optical parameters is discussed. The tremendous self‐assemblies and diverse external field responsiveness make liquid crystals a perfect platform for full‐dimensional manipulation of light.
Helical liquid crystal based planar optics with arbitrary geometric phase modulation and customizable working band is reviewed. Recent progress on broadband transmissive, reflective, transflective, and external fields stimulated band tunable planar optics with helical structures is summarized. Full exploitation of the freedom of light is discussed, which may inspire the helical liquid crystal based multi‐degree light modulation.
Dynamic Multiplexed Holography
In article number 2200011, Peng Chen, Wei Hu, Yan‐Qing Lu, and colleagues from Nanjing University report a new strategy for simultaneous realization of dynamic and ...high‐dimensional multiplexed holography. Via light‐directed liquid‐crystalline chiral superstructures, a photo‐active, bidirectional, polarization‐ and time‐dependent hologram is demonstrated. This novel methodology integrates diverse multiplexing schemes into a single device, facilitating advanced display, security and communication.
Optical Orbital Angular Momentum Processors with Electrically Tailored Working Bands
In article number 2201013, Xiao Liang, Wei Hu, and colleagues schematically illustrate planar optics that ...spatially manipulate light in the entire visible range via a patterned polymer‐stabilized cholesteric liquid crystal with a pitch gradient. An electrically tailored working band can be achieved by varying the helical pitch, enabling mode‐division multiplexing compatible with wavelength‐division multiplexing. This strategy is promising for large‐capacity optical communication and parallel information processing.
