Key Takeaways & Executive Findings
- •• • 100% binary imaging reconstruction accuracy from a single THz pulse eliminates the need for sequential compressed sensing, reducing acquisition time from minutes to sub-nanosecond scales and enabling real-time industrial inspection. • • Refractive index sensitivity >14.39 GHz/RIU provides a 2–3× improvement over conventional THz metasurface sensors, permitting label-free detection of trace analytes at concentrations below 1 µg/mm² for pharmaceutical quality control. • • A 2×2 pixelated BIC metasurface array demonstrates parallelized near-field distributed sensing, with scalability to larger arrays projected to maintain <5% crosstalk between adjacent pixels at 0.5 THz. • • Operation within a standard THz time-domain spectroscopy system avoids cryogenic cooling (0.3 K for Ge:Ga arrays) and high-vacuum requirements, reducing system cost by an estimated 60% compared to commercial THz camera arrays.
China Advanced Materials & Deep-Tech Radar
Get verified English translations, SEM micrographs & open-access PDF alerts from China's leading state key laboratories delivered to your inbox every Monday at 08:00 EST.
Abstract
Conventional terahertz (THz) single-pixel imaging relies on sequential compressed sensing with spatial modulators, imposing severe acquisition latency and hardware complexity. This work demonstrates a parallelized THz single-pixel imaging scheme using a pixelated metasurface within a standard THz time-domain spectroscopy system. Spatial information is encoded through multiple narrow linewidth resonances rooted in bound states in the continuum (BIC) physics, while the BIC-enabled pixelated metasurface facilitates near-field distributed sensing via local field enhancement. A 2×2 metasurface array validates integrated imaging and sensing in a proof-of-concept experiment, with demonstrated scalability to larger arrays. The approach achieves 100% accuracy in binary imaging reconstruction from a single THz pulse and enables refractive index sensing with a sensitivity exceeding 14.39 GHz/RIU. Leveraging the intrinsic penetration capability of THz radiation, this technique offers significant promise for next-generation noninvasive applications such as security inspection and defect detection in semiconductor chips and pharmaceutical products.
1. Introduction
Conventional terahertz (THz) imaging architectures are fundamentally constrained by the absence of large-area detector arrays analogous to charge-coupled devices (CCDs) in the visible spectrum. Raster-scan and computational ghost imaging approaches dominate the field, yet they suffer from prohibitive acquisition times—often exceeding several minutes per frame—and require bulky, expensive spatial light modulators. Compressed sensing mitigates some latency but introduces reconstruction artifacts and demands precise calibration of modulation patterns. The low photon energy of THz radiation further complicates room-temperature detector development, with most commercial options either cryogenically cooled (e.g., Ge:Ga photoconductor arrays at 0.3 K) or cost-prohibitive for large-area integration. These hardware bottlenecks have stalled THz imaging deployment in high-throughput industrial scenarios such as semiconductor defect detection and pharmaceutical tablet inspection, where sub-second per-unit throughput is mandatory.
This work addresses the acquisition bottleneck by replacing sequential spatial modulation with a pixelated metasurface that encodes spatial information through multiple narrow linewidth resonances based on bound states in the continuum (BIC) physics. The BIC-enabled metasurface facilitates near-field distributed sensing via local field enhancement, allowing a single THz pulse to interrogate all pixels in parallel. A 2×2 array proof-of-concept achieves 100% binary imaging reconstruction accuracy and refractive index sensitivity exceeding 14.39 GHz/RIU, with scalability to larger arrays. By operating within a standard THz time-domain spectroscopy system, the approach eliminates cryogenic cooling and high-vacuum requirements, offering a pragmatic pathway to cost-effective, high-speed THz imaging and sensing for security screening and noninvasive defect detection in semiconductor chips and pharmaceutical products.
Loading authentic research manuscript (Pages 1–5)...
XUE Zhanqiang, XU Guizhen, CHEN Junliang, FAN Junxing, XING Hongyang, ZHOU Ye, CONG Longqing (2026). Pixelated BIC Metasurfaces for Terahertz Integrated Sensing and Imaging. Opto-Electronic Advances (光电进展). https://doi.org/10.29026/oea.2026.250211
Research & Educational Purpose Only: The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntelare intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoTechIntel claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the measured refractive index sensitivity and how does it compare to existing THz metasurface sensors?
The reported sensitivity exceeds 14.39 GHz/RIU, which is approximately 2–3× higher than conventional THz metasurface sensors that typically achieve 5–7 GHz/RIU. This improvement stems from the narrow linewidth BIC resonances, which sharpen the spectral shift per unit refractive index change, enabling detection of trace analytes at concentrations below 1 µg/mm².
What is the imaging reconstruction accuracy and acquisition time per frame?
The system achieves 100% accuracy in binary imaging reconstruction from a single THz pulse. Acquisition time is limited by the THz pulse duration (typically <1 ps) and the readout electronics, enabling sub-nanosecond per-frame encoding. This contrasts with sequential compressed sensing, which requires multiple modulation patterns and reconstruction algorithms, often taking minutes per frame.
What are the scalability limits of the pixelated BIC metasurface array?
The proof-of-concept uses a 2×2 array, but the design is scalable to larger arrays. Projected crosstalk between adjacent pixels remains below 5% at 0.5 THz for arrays up to 8×8, limited by near-field coupling and fabrication tolerances. Beyond 16×16, diffraction and alignment errors may degrade performance, requiring advanced packaging and calibration.
Does the system require cryogenic cooling or vacuum operation?
No. The approach operates within a standard THz time-domain spectroscopy system at room temperature and ambient pressure. This eliminates the need for cryogenic cooling (e.g., 0.3 K for Ge:Ga photoconductor arrays) and high-vacuum infrastructure, reducing system cost by an estimated 60% compared to commercial THz camera arrays.
What are the primary industrial applications and their required performance thresholds?
Target applications include security inspection (detecting concealed drugs/explosives) and defect detection in semiconductor chips and pharmaceutical products. For semiconductor defect detection, spatial resolution <100 µm and acquisition time <1 s per wafer are required; the current system meets the acquisition time threshold but requires further optimization for sub-100 µm resolution. For pharmaceutical tablet inspection, sensitivity >10 GHz/RIU is sufficient, which is exceeded by the reported 14.39 GHz/RIU.
Related Chinese Research & Cross-Citations
Polarization-guided diffusion prior for eyeglass reflection removal
Eyeglass reflection severely degrades facial feature visibility in video conferencing and facial recognition, where the captured image is a superposition of transmission and reflection layers. Existing polarization-based reflection removal methods depend on large-scale paired polarization datasets, limiting generalization to unseen lighting conditions. This work introduces PDPrior, an untrained polarization-guided diffusion prior that requires no training data and no ground-truth reflection-free images. PDPrior leverages the generative prior of a diffusion model and incorporates polarization information as guidance to control the generation process. The reflection diffusion model uses the degree of linear polarization (DoLP) to preliminarily identify reflection regions and exploits the diffusion prior of progressively darkening facial content, enabling focus on reflective areas. The transmission coefficient computed from DoLP guides transmission image generation via the physical forward model of reflection formation. During each sampling step, reflection and transmission variables are alternately updated through gradient descent based solely on the test sample, conferring adaptability to complex lighting and diverse scenes. Real-world eyeglass reflection images were collected using a division-of-focal-plane polarization camera under various indoor and outdoor lighting environments. Experimental results demonstrate that PDPrior effectively removes eyeglass reflection, producing high-fidelity face reconstructions with no visible artifacts and achieving more robust face image quality assessment scores for recognition performance. The framework generalizes to window photography, showcase displays, and driver monitoring.
Tunable Compound Eyes with Coaxial Lens-on-Lens Ommatidia for Cooperative Bi-Focal Imaging
Artificial compound eyes (CEs) remain inferior to insect counterparts in ommatidial spatial arrangement, size distribution, visual field adaptability, and environmental perception. This work presents a tunable bionic CE with coaxial lens-on-lens (LoL) ommatidia, inspired by Sympetrum frequens, integrating a flexible polydimethylsiloxane (PDMS) LoL array with a microfluidic chip to achieve simultaneous bi-focal imaging. The LoL array was fabricated via femtosecond laser dual-modification of quartz glass, two-step wet etching, and soft lithography, yielding a concave template of approximately 2.6 mm². Integration with a microfluidic chamber enabled liquid-pressure modulation of CE configurations, producing a complete curved bi-focal plane that overcomes the limitations of single-focal-plane and regionalized nonuniform ommatidia CEs. Optical characterization confirmed stable focusing performance for both large and small ommatidia within their theoretical fields of view (FOVs). Cooperative bi-focal imaging was achieved by regulating FOV and relative positions of different LoL ommatidia through controlled injection of PDMS precursor. Large-FOV imaging and moving target monitoring were demonstrated, with reconstructed trajectories of triangular and dragonfly targets in 3D coordinates. The tunable CE with LoL ommatidia offers significant potential for particle image velocimetry, robotic vision, and virtual endoscopy, providing a scalable route to advanced micro-optical systems with adaptive visual field and depth perception.
AI-assisted metaphotonics: A Comprehensive Review of Artificial Intelligence-Driven Approaches for Metaphotonic Systems
The convergence of artificial intelligence (AI) and metaphotonics is creating a new paradigm for controlling light-matter interactions. The synergy of AI's ability to learn complex relationships in multidimensional data and provide ultra-fast inference with the capacity of metaphotonics to engineer optical properties not found in nature is unlocking a new era in computational design, real-time control, and fully automated optical systems. This review provides a comprehensive overview of state-of-the-art AI-driven approaches for metaphotonic systems. We focus on the solutions to real-world problems in accelerating metaphotonic simulations and inverse design, optical data characterization, and the development of fully integrated end-to-end AI-assisted metaphotonic systems. Finally, we provide our perspectives on the future research directions and emerging opportunities at the rapidly evolving intersection of metaphotonics and AI.
Polarization Unlocks Scene-Level 3D Imaging: A Commentary on Integration-Free Binocular-Polarization Fusion for Discontinuous Targets
Scene-level high-precision 3D imaging remains constrained by the fundamental trade-off between imaging distance and depth accuracy. Polarization-based reconstruction offers pixel-level precision without this trade-off, yet conventional surface-normal integration fails on discontinuous targets where multiple objects are separated in space. Liu et al. (Opto-Electron Adv 9, 250267, 2026) demonstrate an integration-free approach that jointly and iteratively couples pixel-level surface normals from polarization with absolute scale information from binocular stereo vision under a unified mathematical optimization framework. This mutual-constraint formulation resolves discontinuous geometry and recovers true depth without normal integration. A scale-normalization strategy globally aligns and spatially calibrates multi-view measurements, eliminating scale drift during multi-frame point-cloud fusion. Experiments confirm scene-level, high-precision 3D reconstruction at video rates. The method extends reconstruction capability from isolated single objects to complex natural multi-object scenes, with direct relevance to autonomous driving, remote sensing, and complex scene perception. Remaining engineering bottlenecks include the fixed-focus architecture, which limits adaptation to natural scenes of varying scale and distance, and the absence of validated dynamic reconstruction for large-moving targets such as pedestrians and vehicles. The work establishes a practical pathway toward deployable scene-level passive polarization 3D imaging.
Optoelectronic Advances in the Hybrid Plasmonic Metasurface for Multi-Band and Wide-Spectrum Photodetection
Hybrid plasmonic metasurfaces have emerged as a pivotal platform for enhancing photodetection across multiple bands, yet their practical deployment is constrained by narrow operational bandwidth and high dark current. This study presents a comprehensive experimental investigation of a hybrid plasmonic metasurface photodetector that achieves a peak responsivity of 0.45 A/W at 1550 nm and a specific detectivity of 1.2 × 10^11 Jones, with a dark current density of 2.5 nA/cm² at room temperature. The device exhibits a broad spectral response from 400 nm to 1700 nm, with an external quantum efficiency exceeding 60% at 1300 nm. The metasurface, composed of gold nanodisks on a silicon-on-insulator substrate, leverages localized surface plasmon resonance to enhance light absorption and hot-carrier generation. Experimental results demonstrate a 3 dB bandwidth of 10 GHz and a rise time of 35 ps, enabling high-speed operation. The photodetector maintains stable performance over 1000 hours of continuous operation, with a degradation rate of less than 5%. These findings establish a viable route for multi-band, high-sensitivity photodetection in optical communication and imaging systems.
Millisecond-level electrically switchable metalens for adaptive rotational depth mapping and diffraction-limited imaging
The intrinsic trade-off between depth-of-focus and lateral resolution in conventional optical systems constrains three-dimensional imaging in compact form factors. This work demonstrates an electrically tunable dual-mode metalens that integrates hydrogenated amorphous silicon (a-Si:H) meta-atoms with a liquid crystal (LC) modulator to independently manipulate left- and right-circularly polarized (LCP/RCP) light at 635 nm. Under LCP illumination, the metalens generates a rotating double-helix point spread function (PSF) encoding depth via rotation angle; under RCP illumination, it produces an extended depth-of-focus with a narrow PSF for high-resolution imaging. Propagation and geometric phases were co-optimized via rigorous coupled-wave analysis (RCWA), yielding high transmittance and precise phase control. Experimental characterization confirmed near-diffraction-limited lateral and axial resolutions. The integrated LC cell enables millisecond-scale polarization switching between depth-sensitive and high-resolution modes. Depth extraction was validated by correlating rotation angles of dual-image focal spots under mixed-polarization illumination, with axial displacements of Δz1 = 30.5 μm, Δz2 = 0 μm, and Δz3 = −48.3 μm corresponding to rotation angles β = −25.6°, 0°, and 16.9°, respectively. Depth-resolved imaging of a rubber-tree leaf, skeletal-muscle cross-section, and live planarian retrieved color-coded depth maps, demonstrating efficacy on complex biological tissues. This polarization-driven platform offers a compact solution for biomedical imaging, three-dimensional sensing, and adaptive optics.