The rapid development of 6G terahertz communication systems renders it critical to design low-cost and high-performance integrated antennas. Concurrently, orbital angular momentum (OAM), as an emerging physical dimension, shows immense potential in 6G communication and high-resolution imaging. Here, an all-dielectric integrated meta-antenna operating in the 6G terahertz communication window is demonstrated, which can generate a tightly focused vortex beam. By manipulating the propagation phase of terahertz waves, integrated meta-antennas with different topological charges are designed to generate vortex beams carrying OAM, which greatly enhances the design freedom of the antennas. Under physical size constraints, the design concept is demonstrated and experimentally validated at 0.14 THz. The integrated meta-antenna was fabricated using photocuring 3D printing technology. The electric field distributions of the meta-antennas carrying different topological charges are analyzed, and the experimental results show good agreement with the simulations. This work provides a general approach for designing compact and cost-efficient all-dielectric integrated meta-antennas capable of generating vortex beams, which offers broad prospects for applications in high-capacity 6G communication and high-resolution imaging.

A VO 2 –GST metamaterial film is inverse-designed through a physics-based strategy that combines optimization algorithms with the transfer matrix method for angle-insensitive, four-mode dynamic infrared stealth and thermal management.

Chiral metasurfaces play critical role in physics,materials science,pharmacognosy,and commu-nications.To achieve high-performance chiral responses,such as high circular dichroism(CD)and high-quality factors(Q-factors),bound-state-in continuum(BIC),BIC-based metasurfaces have been extensively studied as a promising platform.However,most realized BIC metasurfaces rely on metallic constituents whose high electromagnetic losses and absence of dynamic chirality tuning together impose a severe limit on their practical potential.This paper presents an all-dielectric chiral BIC metasurface.By illumination sym-metry breaking,the metasurface exhibits a CD value of 0.93.Additionally,dynamic tuning of CD is enabled by external optical pumping.This scheme provides a new avenue for dynamically manipulating the chiral metasurface,which can be used to achieve more complex dynamic chiral characterization and applications.

Despite the promise of terahertz (THz) metasurface biosensors, trace detection of small molecules remains a challenge. Herein, a quasi-bound state in the continuum metasurface functionalized with graphene oxide/gold nanoparticles (GO/AuNPs) is reported for the ultrasensitive detection of D-aspartic acid. The synergistic combination of GO-mediated targeted adsorption and AuNP-induced local field enhancement enables robust signal amplification. Mechanistic analysis via a modified Drude model reveals a critical trade-off between local field enhancement and dielectric loss within the composite system. Experimental validation establishes 2 fg/mL as the lowest experimentally measured concentration within an effective detection zone defined by rational GO/AuNPs proportions, where the optimal sensing performance is achieved with a combination of 0.5 mg/mL GO and 15 mu L AuNPs. This work offers novel insights for developing high-performance THz biosensing platforms tailored for early disease diagnosis.

A hydrogel-coated core-offset fiber pH sensor is proposed and demonstrated for sensing the acidic environments with a pH-range of 2 –6. The fiber structure consists of an 800 μm single mode fiber core-offset fused between two sections of 2 mm no-core fiber with an offset of 62.5 μm. The core-offset structure is demonstrated to have a sensitivity of 17714.286 nm/RIU through finite element simulation. The pH sensing is realized by encapsulating a smart hydrogel at the core-offset structure, whose refractive index varies with pH. Within the pH range of 2–6, a cubic polynomial fitting yields a correlation coefficient of 0.999. The sensor shows a linear operating region from pH 3 to 5 with an ultra-high sensitivity of 42.713 nm/pH and a correlation coefficient of 0.998. Additionally, temperature response experiments reveal a sensitivity of up to 1.970 nm/°C, with a corresponding temperature cross-sensitivity of approximately 0.046 pH/°C. By employing a dual-wavelength demodulation method, simultaneous pH and temperature measurement is achieved, effectively eliminating temperature cross-sensitivity. Meanwhile, the experimental for consistence, stability, response time and repeatability are all carried out. It is indicated that the proposed hydrogel-coated core-offset sensor has excellent performance and is expected to have potential applications from environmental to industrial to biomedical.

Active control of terahertz (THz) wave with high quality factor (Q factor) is essential for the advanced THz applications. Due to the intriguing photoelectric conversion efficiencies and optoelectronic characteristics, lead halide perovskite provides more choices for the development of THz technology. In this paper, by hybridizing lead halide perovskite Cs0.05MA0.15FA0.8PbI3 film with quasi-bound states in the continuum (QBIC), optically controlled THz modulators supporting double resonance were designed and investigated. During the ultrafast optical pumping processes with an optical-pump/THz-probe (OPTP), the leakage behavior of both QBIC resonances was strongly affected by the photo-induced carriers in the Cs0.05MA0.15FA0.8PbI3 film and the full recovery time was near to 273.9 ps. Furthermore, the evolution of both QBIC transmission modulations were also analyzed with the numerical simulation. The simulation results showed that the photo-induced free carriers in the Cs0.05MA0.15FA0.8PbI3 film would short the capacitive gap of QBIC resonators, leading to the modulation of THz wave.

To achieve accurate positioning of wire faults in integrated circuits (ICs) and solve the core problem of difficulty in identifying fault points in THz TDR systems in complex electromagnetic environments due to weak reflected signal amplitudes and susceptibility to noise inundation. This study builds a pulse time-domain reflection diagnostic device based on a terahertz time-domain spectroscopy system, innovatively proposes a dual signal enhancement strategy, and for the first time extends the application of this technology system to fault diagnosis of IC interconnect wires. Firstly, the pearson correlation coefficient is used for fault reflection signal feature recognition, and then the moving window integration method that matches the reference pulse length is adopted to amplify weak reflection pulses at the sub-picosecond level. To verify the effectiveness of the method, planar IC samples with dielectric constants of 2.2 (test group) and 3.0 (validation group) were prepared, and open and short circuit fault points ranging from 10 mm to 40 mm were pre-set on them. The experimental results show that in the test group, the maximum positioning error is 1.298 mm (short circuit fault, relative error 12.981 %), and the minimum positioning error is 76 mu m (relative error 0.191 %); In the verification group, the positioning error of the 40 mm short circuit fault is only 123 mu m (relative error -0.331 %), and the accuracy of fault type identification reaches 100 %. This method effectively solves the bottleneck of extracting and identifying weak reflected signals under low signal-to-noise ratio (SNR) conditions, providing a new high-precision diagnostic solution for the field of integrated circuit failure analysis.

We present a reconfigurable all-silicon terahertz (THz) chiral metasurface (RTCM) integrating phase-induced chiral meta-devices with Moir & eacute; phase engineering, to address insufficient dynamic tunability and dimension-limited light field manipulation in existing THz metasurfaces. Conventional THz components, such as refractive lenses and off-axis parabolic mirrors, suffer from wavefront aberrations and limited imaging resolution, while existing metasurfaces lack the ability to simultaneously deliver varifocal lensing and spin-selective transmission. Our RTCM device adopts two cascaded metasurfaces: One with rectangular meta-atoms enables spin-decoupled phase modulation, embedding random phase and focusing phase into orthogonal circular polarization (CP) channels respectively; The other with cylindrical meta-atoms maintains polarization-insensitive propagation phase control. Adjusting their relative rotation angle regulates broadband circular dichroism (CD) response (80 GHz bandwidth) and axial focal length. The initial RTCM achieves over 4.6x dynamic zoom ratio, 34.42-7.43 lambda focal length range, and below -14.02 dB average crosstalk. An improved version with an offset phase factor realizes full-rotation reconfigurable CD, 34.99% average focusing efficiency, and -13.79 dB average crosstalk at 0.5 THz. This mechanically reconfigurable design, free of external voltages or active materials, is highly suitable for portable THz systems and holds significant potential in non-destructive testing and biomedical imaging.

Sensitive detection of epidermal growth factor receptor (EGFR) is of interest for biomarker analysis and related biomedical applications. Here, a functionalized terahertz (THz) metasurface integrating a quasi-bound state in the continuum (Q-BIC) resonance with antibody-functionalized gold nanoparticles (AuNPs) is developed for EGFR detection. An asymmetric split-ring resonator (ASR) array supports the Q-BIC resonance with pronounced electromagnetic field confinement at the sensing surface, while the AuNP-modified interface facilitates antibody immobilization and target-antigen capture. THz transmission measurements show that AuNP functionalization increases the calibration sensitivity from 0.69 to 1.87

Limited by the diffraction limit, the spatial resolution of traditional microwave antennas is difficult to break through the constraint of the wavelength scale, which hinders their application in high-resolution microwave sensing and detection. In this paper, we design an all-dielectric integrated meta-antenna beyond the physical diffraction limit. Firstly, the meta-antenna is functionalized using asymmetric scattering metagrating array based on the generalized Snell's law. High-efficiency focusing beam in the sub-wavelength scale is obtained by manipulating the electromagnetic wavefront. Then, by optimizing the geometric structure of the metagrating to achieve high manipulation efficiency. Finally, the electric field intensity distribution of the generated focal spot is analyzed. The simulation results demonstrate that the manipulation and diffraction efficiencies of the metalens reach 98.50% and 72.56%. The metalens shows a focal spot with the diameter of 0.73 lambda and depth of focus (DOF) of 15.11 lambda. The designed meta-antennas possess the characteristics of long focal depth and high efficiency. Its sub-wavelength focusing property significantly enhances the spatial resolution, which provides a new method for high-precision sensing and detection in the fields such as microwave imaging and non-destructive testing, possessing potential application value.

Off-axis pumped laser is a simple and efficient approach for generating high-order optical vortices. However, despite its apparent scalability, the mode order achievable has stagnated for decades due to the mode purity issue. Here we show that this limitation mainly arises from the mode-family degeneracy of the cylindrically symmetric cavity, with which the Ince-Gauss noise is inevitable. By introducing controlled astigmatism that breaks the cavity symmetry to lift the degeneracy, the mode purity of the off-axis pumped laser can be enhanced significantly. Together with control of transverse-longitudinal mode frequency degeneracy and cavity mode size optimization, this approach enables robust scaling to ultrahigh mode orders. We experimentally demonstrate HG630,0 laser emission with high mode purity directly from the cavity and its transform of LG0,630 optical vortex via astigmatic mode conversion. This work provides a clear route toward scalable high-order structured-light lasers.

Nonradiative resonances demonstrate revolutionary technological potential in capturing incident light, enhancing localized electric field intensity, manipulating far-field scattering, and controlling nonlinear effects at the micro/ nanoscale. Here, we systematically elucidate the low-loss field localization achieved through the interference of electric dipoles in nonradiative anapole modes, while bound states in the continuum (BICs), as idealized nonradiative resonant modes, exhibit perfect field localization capability. These two distinct resonant modes, though based on different physical mechanisms-symmetry-protected mode interference versus topological eigenstate confinement-jointly overcome the performance limitations of conventional radiative systems, offering a disruptive platform for light-field manipulation in ultrasensitive optical sensing. With an aim toward practical biosensing applications, these nonradiative metasurfaces with exceptional light-matter coupling characteristics can be integrated with functionalized colloidal gold and monoclonal tag antibodies, thereby constructing a hybrid immunosensing platform capable of highly selective and label-free detection of free prostate-specific antigen (f-PSA) in complex environmental matrices. Experimental results reveal a pronounced concentration-dependent response toward f-PSA, with an impressive limit of detection down to 10 pg mL-1. Notably, increasing the concentration of target antibodies markedly enhances the capture efficiency of f-PSA by accelerating molecular binding kinetics and promoting saturation of recognition site occupancy. These advances pave the way for next-generation biosensing platforms that combine nanophotonic field enhancement with molecular recognition for clinical diagnostics and environmental monitoring. (c) 2026 Chinese Laser Press

Phase errors induced by platform motion uncertainties significantly degrade image quality in near-field millimeter-wave synthetic aperture radar (SAR) imaging, thus limiting applications for weapon detection and security screening. This article presents a phase autocorrelation correction (PAC) method and applies improvements to the back projection algorithm (BPA). The PAC implements dynamic phase compensation through transfer function modeling of ideal and actual sampling signals. It also uses range dimensional accumulation and Riemann sum approximation for precise extraction of linear phase error factors. The enhanced BPA algorithm embeds phase correction factors in wavenumber domain, improving the phase matching accuracy of matched filtering. The simulation results demonstrate that the proposed algorithm significantly reduces sidelobe interference and enhances the energy focusing characteristics of targets in point target imaging. Practical imaging experiments demonstrate that the proposed algorithm markedly improves complex contour clarity and suppresses background noise. The algorithm maintains effective phase correction even at a 1.25-MHz sampling rate, as evidenced by further experiments, ensuring reliable imaging quality for critical target structures. This novel approach offers a valuable supplement to the field of near-field millimeter-wave SAR imaging and is particularly applicable to applications in sparse-data environments.

Terahertz (THz) technology provides a label-free and nondestructive approach, making it particularly suitable for pesticide residue detection. In this article, we integrate chemical vapor deposition (CVD) graphene with a four-gap square ring metasurface to design an ultrasensitive THz sensor, where the specific current loop distribution and magnetic field confinement induce toroidal dipole resonance, resulting in a resonance peak in the transmission spectrum. By taking advantage of the ability of CVD graphene to shift its Fermi level toward the Dirac point under slight external stimulation, the proposed graphene-integrated toroidal dipole metasurface sensor achieves a detection limit of 126 pg/mL for prochloraz. Moreover, we employ a continuous wavelet transform to convert time-domain signals into 2-D wavelet coefficient intensity maps, enabling a more intuitive comparison of sensing performance with that of traditional 1-D methods. Meanwhile, we extract the maximum wavelet coefficient from the intensity maps and combine it with two 1-D parameters to construct a triangular-pyramid chart (TP-chart) for multidimensional analysis of sensing performance. This work provides an effective approach for trace-level detection, facilitating the application of terahertz technology in pesticide residue analysis.

This article demonstrates the design and implementation of an FPGA-based LiDAR target simulator (LTS) for pulsed-coded LiDAR testing. The simulator employs a hybrid delay architecture integrating multiphase clock sampling and FIFO buffering. By combining coarse and fine timing modules, the system achieves a temporal resolution of 0.5 ns, corresponding to a spatial resolution of 7.5 cm. It also supports an ultralong maximum delay time up to 83.886 ms (12 582-km range), covering simulation scenarios involving long-range targets. In addition, the system supports pulsewidth modulation, allowing it to simulate the temporal broadening of laser pulses caused by environmental factors such as atmospheric turbulence and target scattering, with a resolution of 0.5 ns. Experimental results demonstrate that the proposed approach effectively overcomes the limitations of traditional methods in terms of precision, range, stability, and compatibility with various coding schemes. This work provides a reliable technical foundation for the development and evaluation of pulse-coded laser ranging systems.

A characterization method for terahertz beam in time domain spectroscopy (TDS) systems is proposed, by employing a mask composed of an echelon and a baffle to spatially encode the beam. The beam is scanned horizontally at multiple vertical positions, each corresponding to a distinct measurement plane defined by the echelon’s stepped structure. The scanning step size is set to half the height of a single echelon step. During the scanning process, time-domain signals are acquired from specific regions of the beam. Multivariate linear equations are then constructed based on the encoded spatio-temporal data obtained from different scanning positions. Through inverse reconstruction, a spatial intensity distribution image of the terahertz beam is obtained. Compared with the basic scanning configuration, the imaging resolution is effectively doubled, thereby clearly revealing details of the spot size, shape, and intensity profile. Furthermore, the impact of potential noise on imaging quality is analyzed, demonstrating that excellent reconstruction can be achieved if the ratio of the estimated maximum single-pixel intensity to the noise fluctuation variance is below 0.8 %. In addition to being well-suited for the accurate imaging of small spots, this method eliminates the requirement of large-scale optical path adjustments, enhancing the convenience and controllability of the measurement process.

Extrinsic chiral metasurfaces offer a promising route for controlling chiroptical responses through incident angle variation, yet the simultaneous realization of strong circular dichroism and full-space polarization beam splitting remains challenging. In this work, we propose an all-dielectric extrinsic chiral metasurface that leverages obliquely incident terahertz waves to break in-plane symmetry, thereby activating out-of-plane multipoles and inducing strong spin-selective scattering. At an incident angle of 30°, the metasurface achieves efficient full-space separation of left- and right-handed circularly polarized waves, with a circular dichroism peak exceeding 0.7 near 0.48 THz. Moreover, by varying the incident angle or operating frequency, the polarization state of the reflected wave can be continuously tuned from linear to elliptical to nearly circular, as visualized on the Poincaré sphere. This angle-dependent, full-space polarization manipulation capability highlights the potential of the proposed metasurface for applications in advanced terahertz imaging, LiDAR, and integrated photonic systems.

Halide perovskites are promising candidates for future thermoelectric applications because of their ultralow thermal conductivity and good Seebeck coefficient. Halide perovskites have the advantages of simple preparation processes, low raw material costs, and adjustable crystal structures. However, the low formation energy of halide perovskites usually results in a polycrystalline structure. The grain boundaries can significantly affect the transport of carriers, phonons, and ions, leading to a decrease in the thermoelectric properties. Understanding and mitigating the effects of grain boundaries on particle transport is critical to understanding the thermoelectric properties of halide perovskites. This paper reviews the influence of grain boundaries on the thermoelectric properties of halide perovskites. First, the latest research on the thermoelectric properties of halide perovskites is summarized. Next, the multiple effects of grain boundary structure on the thermoelectric parameters of halide perovskites are analyzed. The use of grain boundary engineering as an effective method to improve the thermoelectric properties of perovskites is emphasized. Finally, we highlight several problems in the research on the thermoelectric properties of halide perovskites, aiming to provide a reference for future studies.