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With the increasing demand of smart electronic textiles, fiber‐shaped sensing devices have rapidly attracted growing interests, in which elastic fiber sensors can monitor a wider range of strains without compromising their flexibility and adaptability with conventional textiles. However, it is still a major challenge to prepare highly sensitive and durable sensing fibers with multifunction. Herein, using a thermally drawn process, highly stretchable elastomeric fibers that are composited with copper particle‐mixed liquid metal electrodes to produce highly elastic piezoresistive strain sensor are fabricated. The composite liquid medal fiber sensor (LMFS) exhibits a strain at break up to 850% and a tensile stress of 6 MPa. When used as a tensile sensor, LMFS can detect large strain levels up to 400%. As a pressure sensor, LMFS can detect an object as light as 0.2 N. The composite fibers can be integrated into a fabric to monitor human motions and Morse code signals. In addition, the fibers can also be applied as an electric heater, the temperature quickly reaches 45 °C at 0.6 V in its original length and 29.3 °C at 0.6 A current with a 250% strain. This work exhibits excellent potential of multifunctional fiber devices in wearable sensing devices. [ABSTRACT FROM AUTHOR]

Heading toward the next‐generation versatile meta‐devices and meta‐systems with increasing complexity, it inevitably demands the cascading and coupling between multi‐layer metasurfaces to create new design space for meta‐optics. However, the accurate requirement for multilayer alignment at the nanoscale is significantly challenging due to the actual fabrication limitation, thus hindering the state‐of‐the‐art meta‐optics device integration and its practical application. Herein, a dynamic meta‐system for augmented reality (AR) holographic display functionality based on a layer‐folded metasurface integrated with an electrical‐driven liquid crystal (LC) platform is originally proposed and realized. By ingeniously folding the optical path between meta‐device vertical space, a beam‐steering metasurface in parallel with the other two holographic metasurfaces placed on a single surface is successfully cascaded. Such a layer‐folded scheme enjoys single‐time lithography processing for multi‐patterning with nanoscale alignment accuracy and avoids any vertical alignment issue. Furthermore, by combining with an electrical‐driven LC tuning scheme, the integrated meta‐system could actively switch independent‐encoded holographic images in real‐time floating in the actual‐world scene. Overall, it is envisioned that such a compact dynamic meta‐system suggests a feasible route for dynamic tunable wearable AR displays, intelligent dynamic displays, multi‐functional devices, etc. [ABSTRACT FROM AUTHOR]

The compactness and programmable versatility make metasurface a promising candidate for optical information encryption and storage. The typical strategy for storage capacity enhancement is essential to expand the metasurface multiplexing channels. Various controllable optical parameters are progressively realized for optical encryption and multiplexing, including wavelength, polarization, orbital angular momentum (OAM), forward/backward illumination, etc. However, as one of the most critical parameters, the incident wavevector (k) direction, namely, the illumination angle, has not been fully explored due to the lack of angular‐encoding capability. Herein, the angular‐encrypted freedom for both amplitude and phase manipulation is theoretically and experimentally achieved by strategically screening the architectural blocks to fulfill the complex‐amplitude requirement. Utilizing the angular‐induced alteration from surface plasmonic resonances (SPRs) and Fabry–Perot (FP) nanocavity resonances, a single angular‐encrypted metasurface has been successfully realized to simultaneously enable quad‐fold independent‐encoding channels, including dual‐holography and dual‐nanoprinting images. Compared to the spatial multiplexing scheme in many previous works, the angular‐encrypted strategy drastically boosts the information storage density and capacity. It is believed that the proposed angular‐encryption finds a new path to achieve multiplexing meta‐devices with fully controlled angular‐resolution and promisingly expands the information capacity for optical encryption with a brand‐new degree of freedom. [ABSTRACT FROM AUTHOR]

The exploit of on‐chip metasurfaces with full optical controllability and multiplexing capability holds great promise for photonic integration circuits (PIC). Despite previous endeavors in metasurfaces controlling guided waves, it still faces critical challenges to realize practical display applications, for instance, augmented reality (AR). Here, a new type of AR based on multiplexed on‐chip meta‐holography is proposed and experimentally demonstrated by integrating judiciously engineered meta‐atoms above waveguide. Through hybridizing detour and Pancharatnam–Berry phases, on‐chip metasurfaces can independently manipulate both guided waves and free‐space light to enable a triple‐channel holography‐multiplexing with independent‐encoding freedom. Eventually, an RGB‐coloring AR hologram free from zero‐order diffraction that can project virtual images into a real‐world environment is realized, showcasing its significant potential for wearable devices (glasses or contact lens) integration. This study finds a feasible route toward multifunctional PIC devices and applications in wearable AR displays, imaging multiplexing, information storage, etc. [ABSTRACT FROM AUTHOR]

Heading towards to intelligent photonic technology, meta‐optics is in the revolutionary process of changing from passive to active controllable devices. Despite various emerging tuning mechanisms exploration and demonstration, they mainly focus on spectral amplitude alternation or near‐field imaging switch. Most tuning schemes inevitably demand quite complicated nanofabrication to incorporate nanotextured active materials, thus limiting its applicable scenarios outside the laboratory. Hence, a practically accessible solution in real life to simultaneously realize multi‐field (both near‐ and far‐field) dynamic displays remains a critical challenge. Here, a practical electric‐driven liquid‐crystal‐integrated metasurface (ELIM) is proposed and demonstrated toward advanced intelligent dynamic display. Through elaborately screening building block (α‐Si nanopillar) geometry to build up a systematic architectural dictionary, conventional spatial‐multiplexing is successfully achieved and the degeneracy for amplitude/phase selections is created and thus any arbitrary multi‐field encryptions are allowed. By leveraging ELIM anisotropic characteristics for orthogonal polarizations, an electric‐driven dynamic tuning is practically realized for the first time to enable quad‐fold dynamic exhibitions, including switchable dual‐nanoprinting (near‐field) and simultaneous dual‐holography (far‐field) images with independent‐encryption freedom. Overall, it is envisioned that meta‐optics integrated with the liquid‐crystal platform can easily find practical applications in real life for intelligent dynamic display, imaging multiplexing, information encryption/security, etc. [ABSTRACT FROM AUTHOR]

As metasurfaces have shown great potential for light manipulation, the majority of optical source parameters have been extensively explored and progressively realized for new degrees of freedom in optical control and multiplexing, including wavelength, polarization, and forward/backward illumination, etc. However, the incident wave vector (k) direction, namely the illumination angle, as one of the critical parameters, has not been fully explored for optical multiplexing due to the lack of angular‐encoding freedom. Here, a general strategy is proposed to realize angular‐multiplexing metasurface based on building up an independent‐encoded amplitude/phase dictionary, in which one can retrieve any arbitrary combination of optical response with different angular illuminations. A series of angular‐multiplexing designs are theoretically and experimentally demonstrated, including angular‐multiplexed meta‐holographs, nanoprintings as well as a hybridized nanoprinting with holography. These studies' numerical calculations and experiments confirm the new degree of freedom for arbitrary encoded amplitude and phase at different illumination angles. The findings establish a new platform for achieving a complexity of functions for angular resolved illumination, and expanding the manipulative capabilities for optical multiplexing. [ABSTRACT FROM AUTHOR]

Metal–insulator–metal (MIM) nanocavity, as a lossy Fabry–Pérot (FP) scheme, has been widely studied for color filter and perfect absorber functionality, which can be integrated into functional photonic devices. However, such triple‐layered MIM still lacks the ability to induce multiple intensity levels for meticulous grayscale imaging because of strong spectral sensitivity to cavity thickness variation. Moreover, the MIM stack remains unexplored to multiplex a near‐field nanoprinting and holographic imaging because it is challenging to break the mutual dependence relation between the intensity and phase shift. Herein, a new film stack of dual‐Fabry–Pérot (DFP) nanocavity is proposed to create triple‐fold freedom in light modulations: intensity, phase shift and operation wavelength, which can be respectively modulated by the top/bottom/total cavity length. By spatially arranging the stepwise nanocavities, the designed DFP pattern can show multiplexing dual‐channel imaging, which encrypts/conceals a grayscale nanoprinting image and simultaneously projects a far‐field holographic image. Such DFP strategy allows for new possibility of independent light modulation and creates new dimensional degree of freedom for thin‐film nanocavity. The proposed functional DFP strategy enriches the subwavelength building block design for metasurfaces and thin‐film stacks, which would promisingly empower advanced applications in information multiplexing, imaging encryption/concealing, and many other related fields. [ABSTRACT FROM AUTHOR]

Liquid immersion on metasurface was earlier demonstrated to realize spectral control. However, it remains a great challenge to achieve tunable phase modulation and versatile beam‐steering performance, which are critical for practical optoelectronic devices. Here, a new liquid‐immersive mechanism with metasurfaces for active beam‐steering is proposed and experimentally realized. Based on the dielectric‐on‐metal nanostructure with selective hydrophilic/hydrophobic properties, the switchable beam‐steering is initiated and successfully presented in the broadband visible regime with a large reflection angle of ≈±30°. Specifically, the beam diffraction direction is tuned between two opposite‐directional channels by water immersion or drying in a repeatable and controllable manner. The proposed straightforward tuning strategy enjoys great convenience in structural patterning and large‐area implementation, instead of requiring any complicated contact patterning or external modulation. This study provides an alternative optical platform for switchable beam‐steering functionality, which is promising for potential applications in tunable display, directional emission, sensing technologies, etc. [ABSTRACT FROM AUTHOR]