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Due to the precise and continuous regulation of phase, holographic encryption based on metasurfaces and liquid crystals (LCs) has been proposed to encrypt the information by manipulating the wavelength, polarization, etc. However, the security cannot be fully guaranteed since the requirements of decoding methods for these schemes are generally not very strict and vulnerable for exhaustive attack. Furthermore, any part of the hologram stolen may lead to the disclosure of the hidden information regardless of the generation mode of phase delay or the selection of media material, so the security needs to be further improved. Here, inspired by Tiger Amulet, embodying the encryption consciousness of ancient China, we propose a simple but effective encryption method and design a “four-in-one” hologram based on photopatterned LCs. Specifically, the most important encrypted image can only be displayed when the four LC holograms in the same group are spliced into a whole according to the designed order. On the contrary, the camouflage information would be displayed if the holograms are placed in the optical path separately or spliced in wrong order. It is even more interesting that with the LC directors tilted with applied external voltages, the holographic efficiency of the LC hologram will change accordingly. This sets further demanding requirement on the decryption condition and thus increases the encryption security. With the advantages of simple design, high security, and low crosstalk, our encryption scheme has great potential in the fields of information hiding and image encryption.

Point-of-care testing of "sample in, answer out" is urgently needed for communicable diseases. Recently, rapid nucleic acid tests for infectious diseases have been developed for use in resource-limited areas, but they require types of equipment in central laboratories and are poorly integrated. In this work, a portable centrifugal microfluidic testing system is developed, integrated with magnetic bead-based nucleic acid extraction, recombinase-assisted amplification and CRISPR–Cas13a detection. The system, with the advantage of its power-supplied active rotating chip and highly programable flow control through integrated addressable active thermally-triggered wax valves, has a rapid turnaround time within 45 min, requiring only one user step. All reagents are preloaded into the chip and can be automatically released. By exploiting a multichannel chip, it is capable of simultaneously detecting 10 infectious viruses with limits of detection of 1 copy per reaction and 5 copies per reaction in plasmid samples and mock plasma samples, respectively. The system was used to analyse clinical plasma samples with good consistency compared to laboratory-based molecular testing. Moreover, the generalizability of our device is reported by successfully testing nasopharyngeal swabs and whole blood samples. The portable device does not require the operation of professional technicians, making it an excellent assay for on-site testing. [ABSTRACT FROM AUTHOR]

Achieving circularly polarized organic ultralong room‐temperature phosphorescence (CP‐OURTP) with a high luminescent dissymmetry factor (glum) is crucial for diverse optoelectronic applications. In particular, dynamically controlling the dissymmetry factor of CP‐OURTP can profoundly advance these applications, but it is still unprecedented. This study introduces an effective strategy to achieve photoirradiation‐driven chirality regulation in a bilayered structure film, which consists of a layer of soft helical superstructure incorporated with a light‐driven molecular motor and a layer of room‐temperature phosphorescent (RTP) polymer. The prepared bilayered film exhibits CP‐OURTP with an emission lifetime of 805 ms and a glum value up to 1.38. Remarkably, the glum value of the resulting CP‐OURTP film can be reversibly controlled between 0.6 and 1.38 over 20 cycles by light irradiation, representing the first example of dynamically controlling the glum in CP‐OURTP. [ABSTRACT FROM AUTHOR]

New two‐dimensional (2D) van der Waals materials are emerging, and their optical parameters urgently need to be acquired experimentally. Most of the reported results come from traditional metrologies used in the past for bulk materials. This unavoidably causes controversy regarding the correctness and accuracy of results, as well as the physical model. Surface/interface plasmon polariton waves are sub‐diffraction‐limited and very sensitive to surroundings. Here, 2D van der Waals materials with metal embodied are presented. Surface/interface exciton‐plasmon polaritons come into being with excitons in 2D transition‐metal dichalcogenides (TMDCs), which are physically taken as the boundary conditions with complex optical conductivities at the interfaces. Complex optical conductivities of 2D TMDCs are measured by means of interference behavior of surface/interface polariton waves. The size requirement of 2D van der Waals materials becomes relaxed, and complex optical conductivities can be measured for single‐crystalline WS2 and MoS2 monolayers with small sizes. Furthermore, a remarkable capability is manifested by yielding complex optical conductivity of van der Waals heterostructures. The proposed metrology can apply to other newly developed materials with modified underlying physical models, as well as various types of 2D van der Waals materials. [ABSTRACT FROM AUTHOR]

Optical edge detection can significantly compress the data volume and is highly pursued in imaging processing. The commonly used methods extract the optical edge information but lose the capability to distinguish colors, which is another key information for imaging. Here, a design for color-selective optical edge detection is proposed and demonstrated with a cholesteric liquid crystal q-plate. The corresponding optical edge detection exhibits a narrow reflection band characteristic due to the one-dimensional photonic crystal configuration of the cholesteric liquid crystal. The monochromatic band is thermally and reversibly tuned ∼300 nm within 5.3 °C. Color-selective optical edge detection is verified by a series of chromatic images. This work introduces a thermally responsive liquid crystal device to release the color dimension of optical edge detection, which may upgrade existing imaging processing techniques. [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]

The role of stannum was investigated in formation and transformation of vanadium-dioxide phase in a deep perspective through characterization methods including Raman spectra, XRD, OM, SEM, UV–vis and electrochemical workstation. The result showed supersaturated stannum atoms could exist in SnxV2-xO5 as amorphous solid solution through non-equilibrium sputtering method, by which the unitary phase Sn-doped VO2 could be obtained under either thermal de-oxidation or thermal de-composition mechanism. Furthermore, cooperating stannum atoms with oxygen vacancies could regulate the formation of vanadium dioxide M1 or M2 phase, in turn engineer the phase transformation (M-R) temperature of VO2. [ABSTRACT FROM AUTHOR]

A fiber‐end‐face‐integrated electrically tunable optical modulator based on graphene field‐effect transistor and the fabrication technique are proposed and demonstrated. The all‐fiber device features a scheme of compactness and high integration when applied to fiber optical system, as well as a low insertion loss since spatial coupling of light is avoided. A reflecting structure is used and the electro‐optic modulator shows vivid modulation when gate voltage gets tuned, with maximum optical reflectance modulation depth over 1% in demonstration. To the best of the authors' knowledge, it is the first time to build an all‐solid gate‐control modulator directly on fiber facet. The fabrication methods introduce workflows of silicon‐on‐insulator processing into the optical fiber end‐face micromachining domain which can be applied to more comprehensive configurations, broadening the path of fiber‐end‐face integrated device. [ABSTRACT FROM AUTHOR]

Liquid crystals (LCs) are key functional materials that are broadly adopted in various fields due to their stimuli‐responsiveness. Recently, LCs with hierarchical architectures have brought new effects to optics and attracted intensive attention. In smectic A phase, the parallel molecular layers are periodically wrapped to form toric focal conic domains (TFCDs) under antagonistic boundary conditions (i.e., hybrid alignment conditions). TFCD shows great potential in nanofabrication and integral imaging. However, the arbitrary tailoring of TFCD is still challenging, and the robustness of hierarchical configuration hinders the tunability. Here, a radial alignment lattice is adopted to guide the local orientation of LCs and thus facilitates predefining the lattice symmetry and domain size of TFCDs. By introducing polymer stabilization and optimizing the composition, the sample simultaneously maintains the director distribution inside smectic layers and possesses the stimuli‐responsiveness of nematic phase at room temperature. By this means, microlens arrays are demonstrated with reversible electrical tunability. The strategy can be extended to other smectic configurations and may upgrade existing dynamic optics. [ABSTRACT FROM AUTHOR]