Jun Wang

With the rapid improvement of equipment integration technology, multi‐spectrum detectors are integrated into compact volumes and widely used for object detection. Confront with this challenge, it is essential to propose a strategy to design a single‐layer metasurface with multi‐spectrum responses in microwave and infrared ranges. In this work, we proposed a method of designing meta‐atoms, which is capable of achieving functional electromagnetic response at microwave and infrared individually. As a demonstration, a metasurface with four different occupation ratios and coding permutation features is designed, fabricated, and tested. In the microwave band, the pixel meta‐atom is designed to realize highly efficient cross‐polarization conversion between 5.0 and 10.0 GHz, which shows the metasurface can behave as ultra‐low Radar Cross Section (RCS) reflectors in the working band; In the infrared band, different occupation ratio of meta‐atoms are designed to realize the infrared emissivity from 0.60 to 0.80 in 3–14 μm, which can be used to exhibit digital infrared camouflage pattern. This work promotes the ability to use single‐layer design to achieve digital infrared camouflage and microwave RCS reduction simultaneously. The one‐layer design is simple in geometry, simplified in process, low cost in economy, and large scale in fabrication, which can promote practical use in compatible microwave stealth and infrared camouflage.

Stealth performance plays an increasingly important role in the evaluation of aircraft performance, while achieving excellent stealth performance in multiple frequency bands simultaneously remains a crucial challenge. Herein, a visible transparent wideband microwave absorber with infrared camouflage function is theoretically presented and experimentally demonstrated. The sample is composed of two radar absorption layers (RALs) and an infrared shielding layer (IRSL). In addition, the magnetic resonance model and the ohmic loss model are employed to strengthen the absorption of the designed RALs >90% in a broadband frequency range of 7–23 GHz with a relative bandwidth of 106.7%, and an average visible transmittance of ≈60%. Furthermore, IRSL is achieved by a designable digital frequency selective surface (FSS), which promotes a compatible design between infrared camouflaged emissivity and microwave absorption. These peculiar properties not only verify the feasibility of the proposed strategy for achieving suitable artificially designed IR digital camouflage patterns to meet various thermal camouflage environments, but also have promising application prospects in multispectral stealth. The additional visible light transparent feature makes it useful in compatible camouflage‐stealth facilities when requiring observing and operating in optical windows.

Artificially-structured functional materials (AFMs) are artificial media that combine the advantages of nature materials and artificial structures to produce excellent and unexpected properties. Ferroelectric materials have key features in possessing spontaneous polarizations, which can be switched by using electric field, temperature, and strain. This review article attempts to provide a comprehensive insight into the current development of ferroelectric composite AFMs, and to introduce a developing subject in realizing multifield controls for tunable functional devices. Some typical ferroelectric materials and their multifield tunable mechanisms are summarized in detail. The incorporation of ferroelectric materials can yield various designs of AFMs to modulate electromagnetic waves. Recent progress of typical designs with different tuning strategies for active AFMs are illustrated and compared, including the metamaterials, metasurfaces, heterojunctions, superlattices, and their hybrid designs. This scientific subject involves interesting research topics of electromagnetism, electronics, optoelectronics, and ferroelectrics, which is significant to bring novel functionalities via multifield controls.

The proposed ITO/ZnS/ITO/ZnS composite film is simple in geometry, functional in use, but complex in mechanism, which may promote its pratical application in infrared-visible compatible camouflage.

High quality factor resonance with extremely narrow line‐width offers an important platform for terahertz (THz) sensing technology as it enables strong light‐matter interaction between THz waves and analyte materials. Lattice mode arising from the collective Rayleigh scattering of metamaterial periodic structures has the ability to strongly confine the electromagnetic waves on the surface that fails to radiate to the far‐field. Herein, for the first time, a strategy is experimentally demonstrated to design THz metasensors, which exhibit dual‐sensitivity of frequency and resonance intensity by coupling the first‐order lattice mode to the toroidal resonance. The frequency sensitivity mainly results from the localized field confinement, whereas the sensitivity of resonance intensity depends on the matching degree between toroidal resonance and lattice mode. It is found that both the frequency shift and resonance intensity show exponential growth with the increase in the analyte thickness. In addition, the sensing performance between toroidal and toroidal–lattice modes is compared to verify the superiority of the dual‐sensitivity property. This work would greatly improve the practical applications of THz sensing technology and open up new opportunities for the realization of slow light devices, multiband narrow filters, and nonlinear systems.

Tuning the carrier behavior in a heterostructure is important for designing well‐performing electro‐optical devices. Scientific research has mainly focused on 2D and layered materials due to their high carrier mobility. Ferroelectrics exhibit a strong response to external fields and are widely employed in microwave and terahertz (THz) tunable devices. By constructing a ferroelectric‐silicon PN heterojunction, a new strategy is proposed to construct a nonequilibrium carrier layer and achieve tunable carrier effects under multifield coupling. Theoretically, the formation of a carrier layer based on the interaction between free carriers and bound surface charges is analyzed, and a design method for PN heterojunction engineering is presented. Experimentally, a PN heterojunction of Ba_0.7Sr_0.3TiO₃ thin film on silicon substrate is constructed, and three tunable carrier effects are achieved. A broadband tunable THz modulator with an amplitude modulation depth of 99.5% is realized, which is superior to other works. The volt–ampere effect of the PN heterojunction can be dynamically adjusted. The shape of the hysteresis loops can be dynamically controlled in real time. This proposed strategy for carrier modulation is a giant step forward in ferroelectrics applications and a path for the development of electro‐optical applications with new materials.