Secret sharing is a promising technology for information encryption by splitting the secret information into different shares. However, the traditional scheme suffers from information leakage in decryption process since the amount of available information channels is limited. Herein, we propose and demonstrate an optical secret sharing framework based on the multi-dimensional multiplexing liquid crystal (LC) holograms. The LC holograms are used as spatially separated shares to carry secret images. The polarization of the incident light and the distance between different shares are served as secret keys, which can significantly improve the information security and capacity. Besides, the decryption condition is also restricted by the applied external voltage due to the variant diffraction efficiency, which further increases the information security. In implementation, an artificial neural network (ANN) model is developed to carefully design the phase distribution of each LC hologram. With the advantage of high security, high capacity and simple configuration, our optical secret sharing framework has great potentials in optical encryption and dynamic holographic display.

This study investigated direct fluorescence generation from a nematic liquid crystal (NLC) NJU-LDn-4 under femtosecond laser excitation. The absorption, transmittance, excitation, and emission spectra of the NLC were assessed. The relationship between the femtosecond pump power and fluorescence intensity was analyzed, revealing a quadratic increase and indicating that two-photon absorption (2PA) is the primary fluorescence mechanism. The LC microstructure was designed using photoalignment technology, allowing the generated fluorescence to reflect the corresponding structure. This research can establish a foundation for tunable LC microstructured fluorescence, with potential applications in fluorescence microscopy and optoelectronics.

Metasurface-based imaging has attracted considerable attention owing to its compactness, multifunctionality, and subwavelength coding capability. With the integration of computational imaging techniques, researchers have actively explored the extended capabilities of metasurfaces, enabling a wide range of imaging methods. We present an overview of the recent progress in metasurface-based imaging techniques, focusing on the perspective of computational imaging. Specifically, we categorize and review existing metasurface-based imaging into three main groups, including (i) conventional metasurface design employing canonical methods, (ii) computation introduced independently in either the imaging process or postprocessing, and (iii) an end-to-end computation-optimized imaging system based upon metasurfaces. We highlight the advantages and challenges associated with each computational metasurface-based imaging technique and discuss the potential and future prospects of the computational boosted metaimager.

Systemic blood circulation is one of life activity’s most important physiological functions. Continuous noninvasive hemodynamic monitoring is essential for the management of cardiovascular status. However, it is difficult to achieve systemic hemodynamic monitoring with the daily use of current devices due to the lack of multichannel and time-synchronized operation capability over the whole body. Here, we utilize a soft microfiber Bragg grating group to monitor spatiotemporal hemodynamics by taking advantage of the high sensitivity, electromagnetic immunity, and great temporal synchronization between multiple remote sensor nodes. A continuous systemic hemodynamic measurement technique is developed using all-mechanical physiological signals, such as ballistocardiogram signals and pulse waves, to illustrate the actual mechanical process of blood circulation. Multiple hemodynamic parameters, such as systemic pulse transit time, heart rate, blood pressure, and peripheral resistance, are monitored using skin-like microfiber Bragg grating patches conformally attached at different body locations. Relying on the soft microfiber Bragg grating group, the spatiotemporal hemodynamic monitoring technique opens up new possibilities in clinical medical diagnosis and daily health management.

Cascaded holography coupled with the secret-sharing scheme has recently gained considerable attention due to its enhanced information processing and encryption capabilities. Here, we propose a new holographic iterative algorithm and present the implementation of cascaded liquid crystal (LC) holography for optical encryption. Each LC layer acts as the secret key and can generate a distinct holographic image. By cascading two LC elements, a new holographic image is formed. Additionally, we showcase the dynamic optical encryption achieved by electrically switching LCs with combined electric keys. This work may offer promising applications in optical cryptography, all-optical computing, and data storage.

使用遗传算法合理地迭代与优化非局域超表面的材料分布，完成了一个一维二阶空间微分器的逆向设计。当入射角小于10°时，该微分器具有与目标函数高度吻合的传递函数。为证明该方法的通用性，采用相同的方式设计了一个拉普拉斯变换器。最后，分别验证了两个器件在实际制造中的可行性以及它们识别图像边缘的效果。

Fluorescence detection is widely used in biology and medicine, while the realization of on-chip fluorescence detection is vital for the portable and point-of-care test (POCT) application. In this Letter, we propose an efficient fluorescence excitation and collection system using an integrated GaN chip consisting of a slot waveguide and a one-dimensional photonic crystal (1D PC) waveguide. The slot waveguide is used to confine the excitation light for intense light–sample interaction, and the one-trip collection efficiency at the end of slot waveguide is up to 14.65%. More interestingly, due to the introduction of the 1D PC waveguide, the fluorescence signal is directly filtered out, and the excitation light is reflected to the slot waveguide for multiple excitations. Its transmittances for the designed exciting wavelength of 520 nm and the fluorescent wavelength of 612 nm are 0.2% and 85.4%, respectively. Finally, based on numerical analysis, the total fluorescence collection efficiency in our system amounts to 15.93%. It is the first time, to our knowledge, that the concept of an all-in-one-chip fluorescence detection system has been proposed, which paves the way for on-chip fluorescence excitation and collection, and may find potential applications of miniaturized and portable devices for biomedical fluorescence detection.

人工设计的光子学器件在现代光学的各个领域都有广阔的应用前景。传统光子学器件的设计通常是基于已知的物理模型，然后通过数值模拟方法对结构进行优化设计。由于器件结构很大程度上依赖于先验模型，所以传统优化设计的自由度是有限的。随着近年来对高性能光子学器件需求的日益增长，具有更高设计自由度的逆向设计方法得到了快速发展。逆向设计方法打破了传统方法的设计局限性，可以在全参数空间中实现高效的参数优化，因此更可能得到具有极限性能的器件结构。本文总结了光子学器件逆向设计的常用方法，并给出了逆向设计在各个光子学领域中的具体应用。随着计算机科学的不断发展，逆向设计方法展现出无与伦比的潜力，有望在各个光学领域中实现更高自由度的光场调控。

Interfacial solar steam generation (ISSG) is a novel and potential solution to global freshwater crisis. Here, based on a facile sol-gel fabrication process, we demonstrate a highly scalable Janus aramid nanofiber aerogel (JANA) as a high-efficiency ISSG device. JANA performs near-perfect broadband optical absorption, rapid photothermal conversion and effective water transportation. Owning to these features, efficient desalination of salty water and purification of municipal sewage are successfully demonstrated using JANA. In addition, benefiting from the mechanical property and chemical stability of constituent aramid nanofibers, JANA not only possesses outstanding flexibility and fire-resistance properties, but its solar steaming efficiency is also free from the influences of elastic deformations and fire treatments. We envision JANA provides a promising platform for mass-production of high-efficiency ISSG devices with supplementary capabilities of convenient transportation and long-term storage, which could further promote the realistic applications of ISSG technology.