The proliferation of advanced photoelectric detectors and multi-spectral reconnaissance platforms has invalidated single-mode camouflage, necessitating synchronous deception across visible, infrared and radar bands. Here, we introduce resonant regulation paradigm into the multi-dimensional camouflage metasurfaces with single-functional-layer (analogous to biological skin), enabling them to achieve integration and synchronization across multiple spectra. Leveraging this strategy, two types of simple but effective single-structural cascaded metasurfaces are designed to achieve collaborative illusion deception disguise and low detectable camouflage. As a proof-of-concept, two types of metasurfaces capable of generating the illusion of an "airplane" are designed and fabricated. In microwave band (8-12 GHz), the metasurfaces can achieve imaging camouflage in near field and scattering reduction in far field. In infrared band (8-14 & micro;m), the infrared thermal illusion patterns are customized by arranging the meta-atoms with low and high emissivity. In visible light band (400-800 nm), the "airplane" patterns can be observed clearly due to the different surface patterns of meta-atoms. By synergizing resonant coupling and decoupling with their matching holographic imaging engines, these metasurfaces in this work concurrently condense structural simplicity and multidimensional camouflage functionality into a single layer, which may trigger further innovation in the design and application of compact multispectral camouflage devices.

In response to multispectral detection threats and functional conflicts or complex structures in existing stealth materials, this paper proposes a flexible multiband stealth metasurface compatible with visible-laser-infrared (IR)microwave spectra. The "three functional layers" architecture-optical camouflage layer (OCL), IR functional layer (IRFL), and microwave functional layer (MFL)-achieves multiband stealth via layered design and process optimization. OCL uses SiO2/ZnS film interference to match visible light colors. IRFL employs an asymmetric Fabry-P & eacute;rot structure based on ultrathin Ag tunneling and surface plasmon polaritons, achieving more than 90% absorption of 1.06 mu m laser and maintaining emissivity below 10% at 2-14 mu m. MFL forms a frequency selective surface by etching OCL and IRFL to enable the transmission of 2-14 GHz electromagnetic waves. Combined with the underlying indium-tin-oxide wave-absorbing structure, it achieves 90% absorption in the X-band. The overall structure, with a thickness of less than 5 mm, exhibits a certain degree of flexibility and visible transparency, adopting mature processes such as electron beam evaporation and laser etching, which are low-cost and suitable for mass production. The designed metasurface realizes multiband stealth with a simple structure, high functional integration, and easy engineering implementation, demonstrating broad application potential in multiband compatible stealth fields. (c) 2026 Chinese Laser Press

Photothermoelectric (PTE) detectors have attracted extensive attention due to the advantages of no external bias, negligible 1/f noise, and low fabrication cost for arrayed and miniaturized devices, and they circumvent the bandgap limitation of traditional photon detectors. However, the practical application of current mainstream PTE materials remains severely hindered by their poor high-temperature stability, especially in harsh scenarios including high-temperature monitoring and industrial waste-heat detection. In this work, CaTiO3 is selected as the PTE material owing to its outstanding high-temperature stability, excellent chemical stability, non-toxicity, and low cost. Nevertheless, intrinsic insulating CaTiO3 possesses neither efficient optical absorption nor favorable thermoelectric properties. Herein, abundant oxygen vacancies are introduced to endow CaTiO3 with broad-spectrum optical absorption via the formation of defect energy levels within the bandgap. Meanwhile, La doping was employed to improve its thermoelectric performance. As a result, the La0.2Ca0.8TiO3 sample achieves a responsivity of ≈300 mA W-1 and a noise level below 5 × 10-9 W Hz-1/2 across a broad spectral range when only intrinsic resistance is considered. It well meets the application needs of harsh civilian environments with no strict requirement for response speed. This work offers a feasible strategy for developing high-performance PTE detectors applicable to high-temperature and harsh working conditions.

SrTiO3 exhibits promising potential in both thermoelectric and optical properties. However, research on these two properties has consistently been carried out in two relatively independent fields. In this work, the regulatory mechanisms of thermoelectric and optical properties were proposed based on photon-excited electron-phonon interactions. Er doping can enhance the photon absorption of SrTiO3 by introducing impurity energy levels, thereby promoting photoexcited electron generation. The introduction of oxygen vacancies (Vo) enhances the interaction between excited electrons and phonons through defect levels, facilitating the conversion of photon energy into thermal energy and subsequently into electrical energy. Additionally, Er-Nb codoping with Vo synergistically optimizes thermoelectric properties, thereby laying a foundation for the regulation of photothermoelectric properties. As a result, significant photothermoelectric conversion was obtained in the Sr0.85Er0.15Ti0.9Nb0.1O3 (Vo) sample. A maximum ZT value of 0.32 at 1073 K was achieved in this sample, representing a 60% improvement over previously reported Nb-doped SrTiO3 samples. The electrical output power of the Sr0.85Er0.15Ti0.9Nb0.1O3 (Vo) sample reaches 3.85 μW under portable 980 nm laser excitation at 260 mW incident power. These findings provide valuable insights into the conversion of light energy to electrical energy in highly absorptive SrTiO3-based thermoelectric materials.

Responding to the growing need for flexible materials with superior electromagnetic shielding performance, this research focuses on synthesizing cobalt ferrite@reduced graphene oxide (CoFe2O4@rGO) nanopowder through a solvothermal synthesis technique. The synthesized nanophase material was then blended with water-based polyurethane to form an EMI slurry, which was subsequently deposited onto a blended fabric base via a simple dip-coating method. A critical factor driving the material's performance lies in the synergistic electromagnetic interaction between rGO and CoFe2O4, which imparts favorable electromagnetic characteristics to the nanocomposite. This interaction enables an exceptional electromagnetic shielding performance. The resulting flexible fabric achieved an EMI shielding effectiveness of 27.6 dB while maintaining an ultraslim thickness of 0.66 mm. Concurrently, the notable flexibility of these blended fabric-based EMI composites, combined with the straightforward dip-coating method fabrication approach, substantially expands the practical application scope of such flexible electromagnetic absorption materials. To conclude, this cost-efficient, flexible, tough, and high-performing EMI shielding fabrics, developed through a simple and scalable synthesis approach, exhibits promising practical potential in civilian applications.

>To adapt to the complex environment where low infrared emissivity and high infrared emissivity coexist, a radar stealth-infrared camouflage compatibility metasurface requires meta-atoms with customized infrared emissivity.Generally, the infrared emissivity is determined by the occupation ratio. However, the high occupation ratio will interfere with the scattering reduction function due to the Lorentz resonance from the metal patch. To address the problem, a method for decoupling Lorentz resonance is proposed in this paper. By shifting the resonant frequency of the metal patch to a high frequency, the Lorentz resonance is suppressed in the frequency band of scattering reduction. To verify the method, a single functional layer metasurface with microwave scattering reduction and customized infrared emissivity is designed. The scattering reduction at 3.5–5.5 GHz is realized through the polarization conversion. Meanwhile, the infrared emissivity of the metasurface can be gradient-designed by changing the occupation ratios of the meta-atoms. Compared with the initial design, the improved metasurface expands the infrared emissivity range from 0.60–0.80 to 0.51–0.80, and the scattering reduction effect remains unchanged.The experimental results agree with the simulated results. The work enriches the infrared emissivity function,which can be applied to camouflage in complex spectrum backgrounds.

Steel materials are widely used in sectors such as transportation and oil pipelines, making the detection of their mechanical properties critically important. This paper proposes an analytical method for yield strength, tensile strength, and elongation of steel materials based on the principle of the magnetostrictive effect. To validate the proposed method, an electromagnetic ultrasonic testing experiment was designed and conducted, from which relevant electromagnetic ultrasonic signal curves were obtained. Characteristic parameters were then extracted from these ultrasonic signals, followed by an analysis of the correlations between the characteristic parameters and mechanical property parameters. The experimental results show that the Pearson correlation coefficients between the magnetostrictive characteristic parameters and mechanical property parameters all exceed 0.85, and the relative standard deviations of all characteristic parameters are less than 10%.

A tetramer metasurface with strong coupling of meta-atoms under C2 symmetry is proposed to realize polarization-dependent bound states in continuum (BICs) with the random forest regressor algorithm assistance. The quality (Q) factor of quasi-BIC correlates with the centralization degree of the tetramer structure, which is determined by the photonic band characteristics. The quasi-BIC is dominated by a hybrid of electric dipole and quadrupole in Ex polarization (Q > 104), whereas only electric dipole dominates quasi-BIC (Q > 103) in Ey polarization. These findings demonstrate a novel strategy to achieve ultrahigh Q-factor resonances in terahertz photonics.

Rapid growth in twist-optics is pushing the boundaries of metasurfaces of twisted photonic structures. Herein, we propose a tetramer-configured metasurface of twisted double split-ring resonators (DSRRs) by a random forest algorithm. A machine learning approach that exhibits periodically tunable polarization-insensitive electromagnetically induced transparency (EIT). The experimental data show a high-quality factor quasi-bound states in the continuum (quasi-BIC) in the terahertz regime. The role of multipoles on EIT and BIC effects is revealed by the coupled Lorentz oscillators (CLO) model. Our results manifest a new approach to tuning the terahertz EIT and BIC effect at ambient conditions.

This paper uses high-permittivity ceramics to design an all dielectric metasurface absorber, which can form a good absorption effect through dielectric resonances. The absorption efficiency can reach over 90 %. This design uses an integrated connected structure, which facilitates the use of mature technologies such as solid-state sintering or 3D printing for production. Ceramic materials have advantages such as high temperature resistance, oxidation resistance, corrosion resistance, and high power resistance. This design method can adjust resonance to achieve absorption of different bandwidths and frequencies, and has potential application value.

Metamaterials provide amazing opportunities for developing frequency selective radiation because of their unique electromagnetic resonance properties. However most frequency-selective thermal radiation metamaterials currently do not have an optical transparency property, which prevents them from being used in some special occasions. Here, an optically transparent frequency-selective thermal radiator is designed and fabricated using the metallic-like properties of ITO. The emissivity of the metamaterial in the atmospheric transparent windows (3.0-5.0 mu m and 8.0-14.0 mu m) is less than 0.1, while the emissivity outside the windows (5.5-7.6 mu m) is very high, thus achieving strong thermal radiation efficiency. Finally, the thermal radiation power of frequencyselective thermal radiator, low-emissivity coatings, and black body was analyzed using the thermal radiation model. Compared to traditional low-emissivity coatings, the advantage of frequency-selective thermal radiators is that it provides an efficient thermal radiation window for the target, further enhancing its infrared stealth capability through radiative cooling.

Thermoelectric and infrared radiation effects are extensively applied in the energy and aerospace sectors; however, the underlying physical mechanisms remain unclear. While numerous studies have been conducted on these effects individually, few have explored their commonalities and intrinsic connections. Thus, investigating the relationship between infrared radiation and thermoelectric properties presents an opportunity for innovative interdisciplinary research. This study focuses on how heat and light influence electrons by examining the relationship between the thermoelectric properties and the infrared radiation properties of rutile Ti1-xNbxO2 (x = 0.01, 0.05, 0.14, 0.20) materials synthesized using a solid-state method. First-principles calculations and doping optimization effectively controlled the Seebeck coefficient and electrical conductivity. Consequently, the Ti 0.8 Nb 0.2 O 2 sample exhibited a high power factor and low thermal conductivity, resulting in a ZT value of 0.24. The sample absorbs infrared light in the 8-14 mu m range, demonstrating a negative correlation between the ZT value and infrared emissivity. This finding offers a novel perspective on the interrelationship between infrared radiation and thermoelectric properties, providing theoretical guidance for the development of multifunctional materials.

Modern radar reconnaissance scenarios are increasingly characterized by crowded electromagnetic spectra and heavily overlapped time-frequency parameters, making traditional parameter-based analysis less reliable due to limited resolution and fixed clustering thresholds. To address this challenge, this paper proposes an adaptive separation method based on the direction of arrival distribution characteristics. By exploiting the evolution of the direction of arrival (DOA) with respect to the time of arrival (TOA) and applying a Hough-transform-based detector, data points from different radar emitters are identified. Subsequently, the distance distribution between data points and their detected lines is analyzed. By jointly examining the distance curve and its histogram, an adaptive decision threshold is derived to achieve robust spatial separation of overlapping signals. Experimental results demonstrate that the proposed method effectively separates radar emitter signals with overlapping time-frequency parameters and provides a reliable foundation for subsequent multidimensional fusion analysis.

Thermoelectric materials are functional materials that directly convert thermal energy into electrical energy or vice versa, and due to their inherent properties, they hold significant potential in the field of energy conversion. In this review, we examine several fundamental strategies aimed at enhancing the conversion efficiency, classification, preparation methods, and applications of thermoelectric materials. First, we introduce an important parameter for evaluating the performance of thermoelectric materials, the dimensionless quality factor ZT, and present the theory of electroacoustic transport in thermoelectric materials, which provides the foundation for enhancing the performance of thermoelectric materials. Second, strategies for optimizing electroacoustic transport properties, carrier concentration, energy band engineering, phonon engineering, and entropy engineering are summarized, emphasizing that energy band engineering presents numerous possibilities for enhancing thermoelectric material performance by tuning the carrier effective mass, energy band convergence, and energy band resonance. By analyzing the importance of various optimization strategies, it is concluded that co-optimization is the primary method for improving the performance of thermoelectric materials in the future. In addition, an overview of the currently available thermoelectric materials is provided, including two categories, classical thermoelectric materials and novel thermoelectric materials, along with a highlight of two thermoelectric material preparation techniques. Finally, the principles of thermoelectric technology are illustrated, its applications in various fields are discussed, problems in the current research are analyzed, and future trends are outlined. Overall, this paper provides a comprehensive summary of optimization strategies, material classifications, and applications, offering valuable references and insights for the researchers in this field, with the aim of further advancing the development of thermoelectric material science.

Due to the rolling friction, it is easy to produce harmful scratches, cracks, blocks and damage on the rail surface. In order to detect and evaluate the damage accurately and efficiently, this paper proposed an evaluation method based on magnetic flux leakage (MFL) detection, where the defect threshold is calculated by using the adaptive threshold method and the impact of noise on the results reduced. With the study on the relationship between the depth, detection speed and signal peak-to-peak value of the manual sample, quantitative statistics is made on the depth of the defect. By calculating the average severity of the damage within a length of the rail, the condition of the section is assessed. During the study, the feasibility of the method is verified by finite element simulation analysis for the three-section damage of the main line of the high-speed railway. The test results show that the method can evaluate the rail surface damage quickly and effectively.