Abstract Hyperspectral imaging acquires spatially resolved spectral signatures, enabling a wide range of applications from scientific research to industrial processes. Traditional microelectron-mechanical systems (MEMS) Fabry–Pérot (FP) spectrometers offer a compact and simple design but are limited by single free spectral range (FSR) operation. This limitation introduces a fundamental trade-off: achieving high spectral resolution necessitates narrowing the operational bandwidth. Furthermore, maintaining such high resolution demands a larger number of sampling channels, which increases the acquisition time for a single hyperspectral image and thereby limits the frame rate. Here, we present a computational hyperspectral imaging framework that achieves broadband spectral coverage and high frame rate without sacrificing spectral resolution. By dynamically modulating the MEMS-FP cavity to span multiple FSRs, we generate a set of low-correlation spectral sampling patterns as spectral encoders. When combined with a tailored reconstruction algorithm, the system accurately decodes spectral information from a significantly reduced number of sampling channels. We experimentally validate the effectiveness of our system through LED array inspection, demonstrating its potential for high-throughput defect detection in LEDs or screen manufacturing lines. Our work presents a strategy that leverages rapidly advancing computational techniques to overcome the limitations of conventional hardware architectures in hyperspectral imaging. This compact and integrable solution is particularly well-suited for deployment in resource-constrained environments.

Abstract Subwavelength focusing of hyperbolic phonon polaritons (HPhPs) offers a powerful strategy for confining light beyond the diffraction limit, enabling extreme energy localization and enhanced light-matter interactions. However, the limited field enhancement, tunability, and scalability of implementations have motivated interest in polaritonic rays—high-momentum modes that offer collimated, diffraction-free propagation and an elevated optical density of states—as a promising alternative for efficient energy transport and deep subwavelength confinement. Yet, dynamic control and functional integration of such modes, particularly tunable in plane focusing, remain largely unexplored. Here, we demonstrate polarization-switchable in-plane focusing of ghost hyperbolic phonon polariton (g-HP) rays in bulk calcite—a monolithic, lithography—compatible platform that intrinsically supports ray-like modes without requiring artificial layering or phase-change engineering. By tailoring the antenna geometry, excitation frequency, and incident polarization, we realize reconfigurable focusing with up to 25-fold electric field enhancement. These results position calcite-based g-HPs as a scalable, low-loss polaritonic platform, offering new opportunities for mid infrared spectroscopy, reconfigurable photonic circuitry, and high-resolution optical sensing.

Abstract Metamaterial-based biosensors (meta-biosensors) offer a versatile platform for label-free detection of biological analytes. However, conventional multi-mode designs often rely on intricate configurations with uncertain mode excitability under free-space incidence. Here, we propose a band-folding-enabled meta-biosensor that supports high density of free-space- excitable modes. Guided by a Fourier-series theoretical framework developed to predict the coupling strengths, numerous symmetry-protected hidden modes are converted into radiative resonances by introducing perturbations into a hexagonal superlattice. We apply this multi- mode platform to phenotype different biological cells at sub-terahertz frequencies. Supported by histopathological validation, we demonstrate that the dense accumulation of intracellular biomass and enlarged nuclei in malignant cells induce a distinct volumetric permittivity contrast. This mechanism could enable rapid differentiation of cancerous phenotypes from the normal counterparts. Our work bridges metamaterial device physics with biological structural insights, broadening the horizon for mode-multiplexed metamaterials in phenotypic screening.

Abstract Exceptional points (EPs) are spectral singularities where eigenvalues and eigenvectors coalesce, typically requiring complex couplings and enabling phenomena like unidirectional propagation. Meanwhile, metasurfaces, composed of artificially engineered arrays of subwavelength structures, enable unprecedented manipulation of electromagnetic waves. Recently, by tuning the coupling within a unit cell to realize an EP in the parameter space, metasurfaces with EPs have provided insights into the manipulation of light’s spin states. However, metasurfaces with EPs based on complex couplings exhibit obvious residual zero-order diffraction in manipulating light’s spin states. Here, we experimentally demonstrate a method to construct EPs in the parameter space without complex couplings within a unit cell, effectively suppressing residual zero-order diffraction. The EPs originate from the superposition of the accumulated phases from tailoring the sizes and relative rotation angles of the two pillars in a compound unit cell, forming nodal lines consisting of EPs in the parameter space. Using terahertz imaging technology, we experimentally observe spin-selective vortex beam generators and terahertz lenses constructed by metasurfaces with EPs in the parameter space. Our finding offers alternative insights to implement spin manipulation in metasurfaces and spin-dependent wavefront engineering devices.

Abstract Exploring the ocean’s vast, water-related environment, covering over 70% of Earth’s surface, remains a formidable challenge due to photon starvation, high-pressure extremes, and complex light-scattering effects below the photic zone. Optical imaging technologies have emerged as transformative tools for full ocean depth exploration, overcoming limitations of traditional acoustic methods through high-resolution, spectrally rich, and temporally precise observations. This review systematically surveys the physical principles, engineering constraints, and state-of-the-art developments in optical imaging from surface waters to the Mariana Trench. We analyze the role of blue-green pulsed lasers in improving imaging quality. We highlight key factors affecting light propagation in seawater. Advanced imaging modalities such as polarized imaging, range-gated imaging, single-photon imaging, streak camera techniques, and ghost imaging (GI) are examined for their capabilities to enhance visibility, resolution, and resilience in turbid, light-limited conditions. Furthermore, we introduce the progress achieved by deep-sea submersibles and their high-performance camera payloads is highlighted, alongside the burgeoning integration of artificial-intelligence-driven image enhancement and restoration frameworks. Collectively, these interdisciplinary innovations chart a new path for unlocking deep-sea frontiers, enabling ecological monitoring, resource mapping, and autonomous guidance in earth’s most inaccessible water-related realms.

Abstract Hole transport layer-free printable mesoscopic perovskite solar cells (p-MPSCs) employing carbon electrodes offer cost-effective fabrication but face efficiency limitations due to suboptimal charge transport in the TiO 2 -based mesoporous electron transport layer (mp-ETL). Here, we develop a TiO 2 @SnO 2 bilayer mp-ETL for p-MPSCs and obtain encouraging performance enhancement. By performing tailored chemical bath deposition of the preformed triple mesoporous scaffold of TiO 2 ETL/ZrO 2 spacer/carbon electrode rather than the mp-TiO 2 alone, the conformal SnO 2 coating is formed without experiencing high-temperature annealing suffering, thus circumventing associated electronic property degradation. This approach enables selective conformal SnO 2 deposition exclusively on mp-TiO 2 , preventing the formation of undesired current leakage pathway in the spacer. Notably, intentional SnO 2 incorporation in the carbon electrode shows no detrimental effects. The conformal SnO 2 coating successfully improves interfacial energy alignment, suppresses non-radiative recombination, and boosts electron transport. The resulting TiO 2 @SnO 2 p-MPSCs achieve a well improved champion power conversion efficiency (PCE) of 22.5%. The bilayer mp-ETL also demonstrates scalability with 18.8% PCE achieved in 57.33-cm 2 minimodules. Furthermore, encapsulated devices exhibit good operational stability, with 90% efficiency retained after 2000-h maximum power point tracking under continuous illumination at 55 ± 5 °C. This work establishes a practical mp-ETL for high-performance printable perovskite photovoltaics. Graphical Abstract A bilayer mp-ETL of TiO 2 @SnO 2 is developed via low-temperature processing for hole-conductor-free, carbon-based fully printable mesoscopic perovskite solar cells, thereby enabling a PCE of 22.5% and 18.8% for 0.1-cm 2 and 57.33-cm 2 devices.

Abstract Conventional electromagnetic cloaking paradigms predominantly necessitate the encasing of static objects within predefined topological enclosures, fundamentally restricting invisibility to fixed, closed geometries. Realizing dynamic, adaptive concealment for arbitrary moving targets within an open, boundary-free aperture remains a formidable challenge. Here, we report a meta-reinforcement-learning metasurface (Meta 2 Surface) that enables the first experimental demonstration of a "transparent cloaking tunnel" (TCT)—an open corridor permitting the undetected passage of diverse objects. Distinguished from traditional adaptive cloak, the Meta 2 Surface employs a sensor-in-the-loop meta-policy governed by a task-adaptive hypernetwork. This architecture fuses real-time sensing with historical interaction trajectories to instantly synthesize impedance strategies that actively nullify object-dependent scattering with millisecond-scale latency. Comprehensive full-wave simulations and microwave experiments confirm robust, high-fidelity cloaking of diverse dynamic targets—varying in shape, size, material, and trajectory—even under abrupt object substitution. By transitioning invisibility from static encapsulation to a dynamic, open architecture, this work establishes a new paradigm for fusing artificial intelligence with reconfigurable metasurfaces to achieve cognitive, large-scale electromagnetic wave control.

Abstract Boron-based scintillators have attracted significant attention due to their high thermal neutron capture cross-section. However, large-area pure boron-based scintillators remain unexplored. Here, an 8-inch pure boron-based thermal neutron scintillator—nano-polycrystalline hexagonal boron nitride (NPhBN) film—was successfully fabricated via high-temperature rapid chemical vapor deposition, achieving full-area uniform and highly efficient luminescence. The NPhBN scintillator exhibits a high photoluminescence quantum yield of 42.5% and an ultrafast neutron response time as low as 14.6 ns, which can be attributed to the carrier confinement effect induced by its nano-polycrystalline structure, thereby enhancing carrier radiative recombination. The neutron radiography systems developed based on this scintillator not only enables large-area multi-object imaging but also clearly reveals the internal structure of metals and organics. Through carrier-confined engineering, this work overcomes the performance limitations of boron-based scintillators, offering a novel technological pathway for large-area multi-object neutron radiography.

Abstract The asymmetric imaging device is a crucial and highly desired component in optical and electromagnetic systems. However, most existing asymmetric imaging devices are based on active or nonlinear materials and are limited to one-directional applications. This paper reports a method to realize asymmetric image transmission and transformation in two opposite directions, respectively, based on diffractive deep neural networks (D 2 NNs), named Janus meta-imager. It is a passive device composed of several diffractive layers that are well-trained using deep-learning-based algorithms. We first experimentally fabricate and validate this Janus meta-imager in the near-infrared (NIR) band, which agrees well with simulation results, thus verifying the asymmetric imaging function. This scheme has the merits of high-speed all-optical processing, low energy consumption, and small size, offering potential applications in all-optical encryption and information storage.

Abstract Increasingly complex electromagnetic environments and congested spectral resources demand the crucial frequency-selective filtering to suppress out-of-band interference during wave manipulation. Here, we present a stacked reconfigurable metasurface that achieves sharp frequency filtering together with multidimensional tunability across polarization and spectral domains. This stacking strategy decouples polarization channels and tailors near-field coupling to realize controllable frequency shifts. A transmission-line theory is analytically established to characterize and control the scattering poles and zeros under varying polarizations and bias voltages, thereby enabling the prediction of the metasurface’s tunable filtering behavior. Experiments validate dynamic polarization selection and continuous shifting of the filtering band. The measured bandpass response exhibits steep transition edges and strong out-of-band rejection, effectively isolating adjacent spectral channels. This design demonstrates the integration of tunability and selectivity across multiple wave dimensions, addressing critical demands for reconfigurability, multiplexing, and interference immunity in modern electromagnetic systems, with broad potential for smart sensing, secure communications, and radar technologies.