There is an urgent need for the application of broadband Microwave Absorption(MA)structures on the leading edges of aircraft wings,which requires the MA structures to possess both the broadband MA performance and grea...There is an urgent need for the application of broadband Microwave Absorption(MA)structures on the leading edges of aircraft wings,which requires the MA structures to possess both the broadband MA performance and great surface conformability.To meet these requirements,we designed and fabricated a flexible bioinspired meta-structure with ultra-broadband MA,thin thickness and excellent surface conformality.The carbonyl iron powder-carbon nanotubes-polydimethylsiloxane composite was synthesized by physical blending method for fabricating the MA meta-structure.Through geometry-electromagnetic optimal design by heuristic optimization algorithm,the meta-structure mimicking to the nipple photonic nanostructures on the eyes of moth can achieve ultra-broadband MA performance of 35.14 GHz MA bandwidth(reflection loss≤–10 dB),covering 4.86–40.00 GHz,with thickness of only 4.3 mm.Through simple fabrication processes,the meta-structure has been successfully fabricated and bonded on wings’leading edges,exhibiting excellent surface conformability.Furthermore,the designed flexible MA meta-structure possesses significant Radar Cross-Section(RCS)reduction capability,as demonstrated by the RCS analysis of an unmanned aerial vehicle.This flexible ultra-broadband MA meta-structure provides an outstanding candidate to meet the radar stealth requirement of variable curvature structures on aircraft.展开更多
β-Ga_(2)O_(3),as one of the important 4th generation semiconductors,is widely used in solar-blind ultraviolet(UV)detectors with a short detection range of 200-280 nm benefiting from its ultra-wide bandgap,strong radi...β-Ga_(2)O_(3),as one of the important 4th generation semiconductors,is widely used in solar-blind ultraviolet(UV)detectors with a short detection range of 200-280 nm benefiting from its ultra-wide bandgap,strong radiation resistance,and excellent chemical and thermal stabilities.Here,a self-powered photodetector(PD)based on an Ag/β-Ga_(2)O_(3) Schottky heterojunction was designed and fabricated.Through a subtle design of electrodes,the pyro-phototronic effect was discovered,which can be coupled to the common photovoltaic effect and further enhance the performance of the PD.Compared to traditional Ga_(2)O_(3)-based PD,the as-used PD exhibited a self-driving property and a broadband response beyond the bandgap lim-itations,ranging from 200 nm(deep UV)to 980 nm(infrared).Moreover,the photoresponse time was greatly shrunk owing to the coupling effect.Under laser irradiation,with a wavelength of 450 nm and a power density of 8 mW cm-2,the photocurrent could be improved by around 41 times compared with the sole photovoltaic effect.Besides,the performances of the Schottky PD were enhanced at both high and low temperatures.The device also possessed long-term working stability.This paper not only re-veals basic physics lying in the 4th generation semiconductor Ga_(2)O_(3) but also sheds light on the multi-encryption transmission of light information using this PD.展开更多
Control signaling is mandatory for the operation and management of all types of communication networks,including the Third Generation Partnership Project(3GPP)mobile broadband networks.However,they consume important a...Control signaling is mandatory for the operation and management of all types of communication networks,including the Third Generation Partnership Project(3GPP)mobile broadband networks.However,they consume important and scarce network resources such as bandwidth and processing power.There have been several reports of these control signaling turning into signaling storms halting network operations and causing the respective Telecom companies big financial losses.This paper draws its motivation from such real network disaster incidents attributed to signaling storms.In this paper,we present a thorough survey of the causes,of the signaling storm problems in 3GPP-based mobile broadband networks and discuss in detail their possible solutions and countermeasures.We provide relevant analytical models to help quantify the effect of the potential causes and benefits of their corresponding solutions.Another important contribution of this paper is the comparison of the possible causes and solutions/countermeasures,concerning their effect on several important network aspects such as architecture,additional signaling,fidelity,etc.,in the form of a table.This paper presents an update and an extension of our earlier conference publication.To our knowledge,no similar survey study exists on the subject.展开更多
[Background and purposes]In recent years,there has been growing attention in academia and industry on the development of high-performance electromagnetic wave(EMW)absorbing materials.However,creating lightweight broad...[Background and purposes]In recent years,there has been growing attention in academia and industry on the development of high-performance electromagnetic wave(EMW)absorbing materials.However,creating lightweight broadband absorbers remains a challenge in terms of practical applications.EMW absorbing materials primarily rely on the magnetic loss of magnetic materials and/or the dielectric loss of dielectric materials to convert EMW energy into thermal energy for dissipation.Among various magnetic materials,Fe_(3)O_(4) plays an irreplaceable role in EMW absorption due to its high saturation magnetization,low cost and compatible dielectric loss in the gigahertz frequency range.Nevertheless,the high density,large matching thickness and narrow absorption bandwidth of Fe_(3)O_(4) pose significant challenges for practical applications.In contrast,one-dimensional(1D)structures not only retain the characteristic properties of lightweight,chemical stability and high dielectric loss,but also exhibit anisotropic structures and large aspect ratios.Additionally,researchers have found that the minimum reflection loss(RL)of hollow carbon materials with mesopores is nearly four times that of non-porous hollow carbon materials and nine times that of dense carbon materials.According to Maxwell's EMW theory,composites consisting of Fe_(3)O_(4) and one-dimensional(1D)mesoporous carbon materials can leverage their respective advantages by optimizing the composition and structure of the composites to balance u,and Er,thereby enhancing EMW absorption performance.Additionally,numerous studies have demonstrated that composites composed of multi-component heterostructures significantly enhance the EAB.This enhancement is primarily ascribed to the numerous interface polarization losses generated by the additional heterostructure interfaces,which also improve the overall impedance matching of the composites.In this study,we leverage the advantages of magnetic/carbon composites,one-dimensional(1D)mesoporous carbon and multi-component heterostructures to prepare a composite of 1D mesoporous carbon-coated manganese oxide(Mn_(3)O_(4) and MnO,denoted as Mn_(x)O_(y))embedded with Fe_(3)0_(4) nanoparticles(Mn_(x)O_(y)/C@Fe_(3)O_(4)).This composite was synthesized and its formation mechanism and microstructure were analyzed in detail.At the same time,the influence of this Mn_(x)O_(y)/C@Fe_(3)O_(4) structure on EMW properties and absorbing performance was further discussed.[Methods]Firstly,MnO_(2) nanowires were synthesized by using a simple hydrothermal method.Then,the MnO_(2) nanowires served as templates for the synthesis of MnO_(2)/PDA@Fe^(3+)composites through the in-situ polymerization of dopamine and Fe^(3+)adsorption.Finally,1D mesoporous carbon-coated manganese oxide composite embedded with Fe_(3)O_(4) nanoparticles(Mn_(x)O_(y)/C@Fe_(3)O_(4))composites were obtained after heat treatment at 550℃ in N_(2).The crystal structure of the samples was analyzed using X-ray diffractometer with Cu Ka irradiation.Scanning electron microscopy(SEM)and high-resolution transmission electron microscopy(TEM)were used to observe microstructure and morphology of the samples.Nitrogen sorption measurements were obtained at 77 K on a Quantachrome surface area and pore size analyzer to measure the specific surface area and pore size distribution.XPS analysis was performed on X-ray photoelectron spectrometer with monochromatic Al Ka radiation.Magnetization curves of the samples were recorded with a Quantum Design physical property measurement system(PPMS-9)at room temperature.The electromagnetic parameters of the Mn_(x)O_(y)/C@Fe_(3)O_(4) composites were measured using an Agilent N5230C network analyzer in the frequency range of 2-18 GHz.For electromagentic testing,the Mn,Oy/C@Fe34 composites and paraffin wax were mixed at 50°C according to the mass ratio of 15 wt.%,20 wt.%and 25 wt.%,and pressed in a special mold to make coaxial rings(inner diameter=3.04 mm,outer diameter-7 mm),which were denoted as S-1,S-2 and S-3,respectively.[Results]SEM images illustrate the preparation process of iD mesoporous carbon-coated manganese oxide embedded with Fe3O4 nanoparticles composites(Mn_(x)O_(y)/C@Fe_(3)O_(4)).Most of the manganese oxide(Mn,Oy)was reduced to granular after heat treatment,while the outer carbon layer remains its 1D morphology and the carbon layer is interspersed with Fe_(3)O_(4) nanoparticles.The diffraction peaks of MnO_(2) nanowires align well with the body-centered tetragonal a-MnO2.For the Mn_(x)O_(y)/C@Fe_(3)O_(4) composites,the signals of α-MnO_(2) disappears,followed by the emergence of Mn_(3)O_(4) and three prominent diffraction peaks for the cubic MnO.In addition,four weak diffraction peaks correspond to the magnetite Fe_(3)O_(4),consistent with the HRTEM results.The corresponding nitrogen adsorption-desorption isotherm and pore size distribution curve are presented to further analyze the mesoporous structure of composite.The surface composition and element valence states of the Mn_(x)O_(y)/C@Fe_(3)O_(4) composite were investigated by using XPS.The polarization relaxation processes were analyzed according to the Debye theory which describes the relationship between e'and e".Besides the polarization loss,the contribution of the conduction loss plays an important role for the overall dielectric loss.The magnetization curve of Mn_(x)O_(y)/C@Fe_(3)O_(4) exhibits typical ferromagnetic behavior.The permittivity parameter(Co),defined as Co=u"(u)^(-2)f^(-1) determine the contribution of eddy current effect to magnetic loss.The tand values are all larger than those of tand,for the three samples,indicating that the loss capacity of Mn_(x)O_(y)/C@Fe_(3)O_(4) composites is mainly derived from the dielectric loss.Although tand,is smaller,it plays an important role in improving the impedance matching of Mn_(x)O_(y)/C@Fe_(3)O_(4) composites.When the filler loading is 15 wt.%,the RL of sample S-1 is about-10.0 dB at the thickness of 1.5 mm with narrow EAB.As the filler loading increased to 20 wt.%,the RL of sample S-2 reached-62.0 dB at a thickness of 2.2 mm and the EAB was 6.4 GHz at a small thickness of 1.7 mm.When the filler loading is further increased to 25 wt.%,the microwave absorption performance of sample S3 decreased significantly with a little region of RL<-10.0 dB at the thickness of 5.0 mm.The values of[Zin/Zol of the three samples at thicknesses of 1.5-5.0 mm were calculated.Due to good impedance matching of S-2,the incident EMW can enter the material and then can be dissipated through dipole polarization loss,interface polarization loss,conduction loss,eddy current loss and natural ferromagnetic resonance loss.[Conclusions]1D Mn_(x)O_(y)/C@Fe_(3)O_(4) was synthesized via a process involving the coating of polydopamine,adsorption of Fe(ll)salts and heat treatment,using MnO_(2) nanowires as templates.The multi-component heterostructure of the Mn_(x)O_(y)/C@Fe_(3)O_(4) composite(Mn_(3)O_(4),MnO,Fe_(3)O_(4),and C)enhances the interfacial interactions between the different phases,providing increased interface polarization loss under the action of an alternating electromagnetic field.The numerous defects and terminal groups in the mesoporous carbon provide abundant dipole polarization centers.Additionally,the presence of mesopores reduces the weight of the material while increasing the multiple scattering losses of the electromagnetic waves within the material.The ID carbon structure in the matrix forms a conductive network between adjacent fibers,facilitating electron migration and transition,thereby enhancing conductive loss.The incorporation of magnetic Fe_(3)O_(4) nanoparticles introduces eddy current loss and natural ferromagnetic resonance loss,thus increasing magnetic loss.Moreover,the synergistic effect between dielectric and magnetic losses improves the impedance matching of the material,leading to excellent EMW absorption performance.展开更多
Broadband near-infrared(NIR)luminescent materials have shown great promise in applications such as optical communication,biomedicine,and optoelectronic devices.However,the current research is focused on phos⁃phors and...Broadband near-infrared(NIR)luminescent materials have shown great promise in applications such as optical communication,biomedicine,and optoelectronic devices.However,the current research is focused on phos⁃phors and glasses,and it is important to develop broadband NIR luminescent nanomaterials.Here,we report an erbi⁃um-sensitized core-shell nanocrystal design for broadband NIR emission.Based on the structural design with suitable dopings of Tm^(3+)and Ho^(3+),the broadband NIR emission covering 1.5-2.1μm region is achieved under 980 nm and 808 nm excitations.Moreover,the emission intensity is further enhanced by introducing Yb^(3+)and Nd^(3+)into the sam⁃ple,respectively,and the energy transfer processes between them are systematically discussed.Our results present a novel approach for developing broadband NIR luminescent materials and devices.展开更多
Two-dimensional perovskite ferroelectric which strongly couple ferroelectricity with semiconducting properties are promising candidates for optoelectronic applications.However,it is still a great challenge to fabricat...Two-dimensional perovskite ferroelectric which strongly couple ferroelectricity with semiconducting properties are promising candidates for optoelectronic applications.However,it is still a great challenge to fabricate self-powered broadband photodetectors with low detection limit.Herein,we successfully realized self-powered broadband photodetection with low detection limit by using a trilayered perovskite ferroelectric(BA)_(2)EA_(2)Pb_(3)I_(10)(1,BA=n-butylamine,EA=ethylamine).Giving to its large spontaneous polarization(5.6μC/cm^(2)),1 exhibits an open-circuit voltage of 0.25 V which provide driving force to separate carriers.Combining with its low dark current(~10^(-14)A)and narrow bandgap(Eg=1.86 e V),1 demonstrates great potential on detecting the broadband weak lights.Thus,a prominent photodetection performance with high open-off ratio(~10^(5)),outstanding responsivity(>10 m A/W),and promising detectivity(>1011Jones),as well as the low detecting limit(~nW/cm^(2))among the wide wavelength from 377 nm to637 nm was realized based on the single crystal of 1.This work demonstrates the great potential of 2D perovskite ferroelectric on self-powered broadband photodetectors.展开更多
Dion-Jacobson (DJ) phase hybrid perovskites have been proven to improve the photovoltaic performance of the devices due to its unique structure.At present,some DJ hybrid perovskites have been reported and used for pho...Dion-Jacobson (DJ) phase hybrid perovskites have been proven to improve the photovoltaic performance of the devices due to its unique structure.At present,some DJ hybrid perovskites have been reported and used for photodetection filed,but most of them are based on lead-bromide systems,which is not conducive to construct broadband photodetection devices due to the limitation of intrinsic absorption.Herein,we constructed a bilayered DJ hybrid perovskite (3AMPY)(EA)Pb_(2)I_(7)(3AMPY^(2+)is 3-(aminomethyl)pyridinium,EA^(+)is ethylammonium) using an aromatic spacer,which exhibit large current on/off ratios of 10~4under 520 and 637 nm illumination.In particular,the single crystal device based on (3AMPY)(EA)Pb_(2)I_(7)shows a distinguished detectivity of 7.4×10^(12)Jones and a high responsivity of 0.89A/W under 637 nm illumination.Such finding not only enriches the quantities of DJ hybrid perovskites,but also provides useful assistance for constructing high-performance optoelectronic device in the future.展开更多
Metasurfaces composed of two-dimensional nanopillar arrays can manipulate light fields in desirable ways and exhibit the unique advantage of beam steering.Here,we experimentally demonstrate a metasurface-based wide-an...Metasurfaces composed of two-dimensional nanopillar arrays can manipulate light fields in desirable ways and exhibit the unique advantage of beam steering.Here,we experimentally demonstrate a metasurface-based wide-angle broadband all-dielectric blazed grating with an extreme incident angle of up to 80°,which is achieved by optimizing the wide-angle phase shifts and transmissivities of the unit cells.It exhibits a maximum diffraction efficiency of 72%and a high average efficiency of 64%over a wide range of incident angles from−80° to 45° at 1.55μm.Moreover,the proposed grating has a broad bandwidth of 200 nm(1.45-1.65μm),and average efficiencies of more than 50%can be achieved experimentally over the same incidence angles.Our results may pave the way for the creation of novel and efficient flat optical devices for wavefront control.展开更多
This paper presents a tunable and polarization-insensitive wideband metamaterial absorber based on single-layer graphene.By comparing the simulated experimental data with theoretical derivations,it was found that the ...This paper presents a tunable and polarization-insensitive wideband metamaterial absorber based on single-layer graphene.By comparing the simulated experimental data with theoretical derivations,it was found that the absorbance of the material can be sustained above 90%in the frequency range of 2.78 to 7.14(4.36)THz,of which the absorption rate exceeds 99%in the frequency range of 4.1–4.54(0.44)THz,and remarkably,perfect absorption is achieved at4.32 THz.In the range of 2.78–7.14 THz,the average absorption rate is 96.1%,by adjusting the physical size of the graphene layer pattern,we can modify the working band gap of the absorber.By applying a voltage to modulate the Fermi level of graphene,we can increase the absorption bandwidth.When the chemical potential is 1.0 e V,at the bandwidth of 4.36 THz,its absorption rate exceeds 90%.The working principle of absorbing materials was deeply explored using the principles of electromagnetic field distribution and impedance adaptation.Through detailed analysis of different polarization states and incident angles,we found that the absorber is not sensitive to polarization due to its symmetrical structure,and found that it exhibits low sensitivity at incidence angles.In addition,after comparative analysis,significant differences were observed in the absorption efficiency of the absorber under various relaxation time conditions,and the obtained data were elaborated in detail using the carrier mechanism of plasma vibration.We found that in addition to obtaining an almost perfect absorber with wide band by adjusting the parameters,it is also feasible to obtain an approximately narrow band absorber by changing the relaxation time without having to remanufacture the structure.The absorber offers several advantages,including tunability,a wide absorption band,a high absorption rate,polarization insensitivity,and a simple structure.Therefore,this absorber exhibits great potential for absorption,monitoring,and sensing in the terahertz band.展开更多
This paper presents a compact broadband antenna that overcomes bandwidth limitations in a diamond nitrogenvacancy(NV)center-based quantum magnetic sensor.Conventional antennas struggle to achieve both broadband operat...This paper presents a compact broadband antenna that overcomes bandwidth limitations in a diamond nitrogenvacancy(NV)center-based quantum magnetic sensor.Conventional antennas struggle to achieve both broadband operation and compact integration,restricting the sensitivity and dynamic range of the sensor.The broadband antenna based on a dualfrequency monopole structure achieves a bandwidth extension of 777 MHz at the Zeeman splitting frequency of 2.87 GHz,with the dual resonant points positioned near 2.87 GHz.Additionally,high-resolution imaging of the microwave magnetic field on the antenna surface was performed using a diamond optical fiber probe,which verified the dual-frequency design principle.Experimental results using the proposed antenna demonstrate the outstanding performance of the NV centerbased magnetic sensor:a sensitivity of 55 nT/Hz^(1/2)and a dynamic range of up to 54.0 dB.Compared to sensors using conventional antennas,the performance has been significantly improved.展开更多
A polarization converter with broadband polarization characteristics and capable of dynamic reconfiguration is proposed.By introducing out-of-plane degrees of freedom,dynamically tunable broadband and high-efficiency ...A polarization converter with broadband polarization characteristics and capable of dynamic reconfiguration is proposed.By introducing out-of-plane degrees of freedom,dynamically tunable broadband and high-efficiency linear polarization conversion within the wavelength range of 2000-2800 nm is achieved.Research results indicate that when a two-dimensional(2D)split-ring resonator(SRR)is irradiated by a low-dose focused ion beam,it will deform upward and transform into a three-dimensional(3D)SRR,achieving a linear polarization conversion efficiency of over 90%.The 3D SRR can be driven by electrostatic force to return to the 2D SRR state,thereby realizing the dynamic reconfiguration of this polarization converter.By changing the applied voltage and adjusting the structural parameters,a tailored polarization converter that exhibits broadband performance and high polarization conversion efficiency is also achieved.The results may provide novel ideas and technical methodologies for various applications such as polarized optical imaging,emerging display technologies,polarized optical communication,and optical sensing.展开更多
The performance breakthroughs of some stealth materials have benefited from incorporating biomimetic concepts,and the design ideas of wave-absorbing metamaterials have been greatly broadened.How-ever,stealth materials...The performance breakthroughs of some stealth materials have benefited from incorporating biomimetic concepts,and the design ideas of wave-absorbing metamaterials have been greatly broadened.How-ever,stealth materials developed based on a single biological structure still have limitations regarding overall performance and design freedom.Herein,a dual-structure element combination model with a butterfly-wing porous structure and moth-eye raised structure arranged in an orderly manner is estab-lished.Carbonyl iron and polyurethane are mixed as wave absorbents,and the model is utilized to make a biomimetic metamaterial(CSMA),which has an absorption rate of more than 90%at 6.07-18 GHz,achieving broadband effective absorption.It has been verified that the two biostructures designed after an ordered arrangement show synergistic effects in the combined model,and the cooperation between the structures induces the formation of current vector vortices,which are able to induce microwave losses to broaden the effective absorbing bandwidth.Further,the model has the combined application performance of polarization insensitivity,strong stability of oblique incidence,and low bistatic RCS.Such a thought based on the combination of multiple components provides an effective strategy for the design of broadband-absorbing metamaterials.展开更多
Full-Stokes polarimeters can detect the polarization states of light,which is critical for the next-generation optical and optoelectronic systems.Traditional full-Stokes polarimeters are either based on bulky optical ...Full-Stokes polarimeters can detect the polarization states of light,which is critical for the next-generation optical and optoelectronic systems.Traditional full-Stokes polarimeters are either based on bulky optical systems or complex metasurface structures,which cause the system complexity with unessential energy loss.Recently,filterless on-chip full-Stokes polarimeters have been demonstrated by using optical anisotropic materials which are able to detect the circularly polarized light.Nevertheless,those on-chip full-Stokes polarimeters have either the limited detection wavelength range or relatively poor device performance that need to be further improved.Here,we report the high performance broadband full-Stokes polarimeters based on rhenium disulfide(ReS_(2)).While the anisotropic structure of the ReS_(2)introduces the in-plane optical anisotropy for linearly polarized light(LP)detection,Schottky contacts formed by the ReS_(2)-Au could break the symmetry,which can detect circularly polarized(CP)light.By building a proper model,all four Stokes parameters can be extracted by using the ReS_(2)nanobelt device.The device delivers a photoresponsivity of 181 A/W,a detectivity of 6.8×10^(10)Jones and can sense the four Stokes parameters of incident light within a wide range of wavelength from 565-800 nm with reasonable average errors.We believe our study provides an alternative strategy to develop high performance broadband on-chip full-Stokes polarimeters.展开更多
Tunable mid-infrared lasers are essential for optical sensing and imaging.Existing technologies,however,face challenges in simultaneously achieving broadband spectral tunability and ultra-rapid scan rates,limiting the...Tunable mid-infrared lasers are essential for optical sensing and imaging.Existing technologies,however,face challenges in simultaneously achieving broadband spectral tunability and ultra-rapid scan rates,limiting their utility in dynamic scenarios such as real-time characterization of multiple molecular absorption bands.We present a high-speed approach for broadband wavelength sweeping in the mid-infrared region,leveraging spectral focusing via difference-frequency generation between a chirped fiber laser and an asynchronous,frequency-modulated electro-optic comb.This method enables pulse-to-pulse spectral tuning at a speed of 5.6 THz∕μs with 380 elements.Applied to spectroscopic sensing,our technique achieves broad spectral coverage(2600 to 3780 cm−1)with moderate spectral resolution(8 cm−1)and rapid acquisition time(-6.3μs).Notably,the controllable electro-optic comb facilitates high scan rates of up to 2 Mscans∕s across the full spectral range(corresponding to a speed of 60 THz∕μs),with trade-offs in number of elements(-30)and spectral point spacing or resolution(33 cm−1).Nevertheless,these capabilities make our platform highly promising for applications such as flow cytometry,chemical reaction monitoring,and mid-infrared ranging and imaging.展开更多
Broadband photothermal and photoacoustic agents in the near-infrared(NIR)biowindow are of significance for cancer phototheranostics.In this work,Pt Cu nanosheets with an average lateral size of less than 10 nm are syn...Broadband photothermal and photoacoustic agents in the near-infrared(NIR)biowindow are of significance for cancer phototheranostics.In this work,Pt Cu nanosheets with an average lateral size of less than 10 nm are synthesized as NIR photothermal and photoacoustic agents in vivo,which show strong light absorption from NIR-I to NIR-II biowindows with the photothermal conversion efficiencies of 20.4%under 808 nm laser and 32.7%under 1064 nm laser.Pt Cu nanosheets functionalized with folic acidmodified thiol-poly(ethylene glycol)(SH-PEG-FA)present good biocompatibility and 4T1 tumor-targeted effect,which give high-contrast photoacoustic imaging and efficient photothermal ablation of 4T1 tumor in both NIR-I and NIR-II biowindows.Our work significantly broadens applications of noble metal-based nanomaterials in the fields of cancer phototheranostics by rationally designing their structures and modulating their physicochemical properties.展开更多
Considering the challenges posed by severe electromagnetic wave pollution and escalating international tensions,there is a critical need to develop advanced electromagnetic wave absorbing(EMWA)materials that integrate...Considering the challenges posed by severe electromagnetic wave pollution and escalating international tensions,there is a critical need to develop advanced electromagnetic wave absorbing(EMWA)materials that integrate radar stealth and thermal insulation capabilities.In this study,we have synthesized three-dimensional(3D)porous composites comprising V_(2)O_(3) nanoparticles embedded in Juncus effusus cellulose-derived carbon aerogels(VCA)using a self-templating method followed by high-temperature pyrolysis.The V_(2)O_(3) nanoparticles possess a 3D V-V framework and a relatively narrow bandgap,facilitating the Mott transition for enhanced conductivity.Furthermore,their uniform dispersion on hollow carbon tubes of Juncus effusus promotes efficient electron transfer and creates numerous heterogeneous interfaces.Consequently,VCA-2 demonstrates outstanding EMWA performance,achieving a minimum reflection loss of−63.92 dB at a matching thickness of 2.0mm and a maximum effective absorption bandwidth of 8.24 GHz at a thickness of 2.44mm,covering nearly half of the tested frequency range.Additionally,the radar cross-section reduction reaches a peak value of 29.40 dB m^(2),underscoring the excellent radar stealth capabilities of the material.In summary,VCA exhibits exceptional EMWA,radar stealth,and thermal insulation properties,highlighting its potential for multifunctional applications in EMWA material development.展开更多
Optically transparent microwave absorbers and multi-band stealth have extensive potential applications in military defense and wireless communication fields, and thus have attracted considerable attention. So far,most...Optically transparent microwave absorbers and multi-band stealth have extensive potential applications in military defense and wireless communication fields, and thus have attracted considerable attention. So far,most related work is based on inorganic transparent conductive metasurfaces. In this paper, we proposed and experimentally demonstrated a flexible, broadband and optically transparent microwave absorber using an organic metasurface. The metasurface absorber is composed of a sandwich structure, in which electric resonances and magnetic resonances are induced resulting in broadband absorption. A spraying process was developed to prepare this metasurface absorber. Both simulations and experiment show that this metasurface has broadband microwave absorption and good optical transparency. We further found that by using a multi-layer structure, visible, radar,and infrared stealth(multi-band stealth) can be achieved simultaneously. With the advantages of excellent foldability and low cost, the proposed metasurfaces may have applications in military and wireless communication fields.展开更多
Reverse design of highly GeO2-doped silica optical fibers with broadband and flat dispersion profiles is proposed using a neural network(NN) combined with a particle swarm optimization(PSO) algorithm.Firstly,the NN mo...Reverse design of highly GeO2-doped silica optical fibers with broadband and flat dispersion profiles is proposed using a neural network(NN) combined with a particle swarm optimization(PSO) algorithm.Firstly,the NN model designed to predict optical fiber dispersion is trained with an appropriate choice of hyperparameters,achieving a root mean square error(RMSE) of 9.47×10-7on the test dataset,with a determination coefficient(R2) of 0.999.Secondly,the NN is combined with the PSO algorithm for the inverse design of dispersion-flattened optical fibers.To expand the search space and avoid particles becoming trapped in local optimal solutions,the PSO algorithm incorporates adaptive inertia weight updating and a simulated annealing algorithm.Finally,by using a suitable fitness function,the designed fibers exhibit flat group velocity dispersion(GVD) profiles at 1 400—2 400 nm,where the GVD fluctuations and minimum absolute GVD values are below 18 ps·nm-1·km-1and 7 ps·nm-1·km-1,respectively.展开更多
The construction of carbon nanocoil(CNC)-based chiral-dielectric-magnetic trinity composites is considered as a promising approach to achieve excellent low-frequency microwave absorption.However,it is still challengin...The construction of carbon nanocoil(CNC)-based chiral-dielectric-magnetic trinity composites is considered as a promising approach to achieve excellent low-frequency microwave absorption.However,it is still challenging to further enhance the low frequency microwave absorption and elucidate the related loss mechanisms.Herein,the chiral CNCs are first synthesized on a threedimensional(3D)carbon foam and then combined with the FeNi/NiFe_(2)O_(4) nanoparticles to form a novel chiral-dielectric-magnetic trinity foam.The 3D porous CNC-carbon foam network provides excellent impedance matching and strong conduction loss.The formation of the FeNi-carbon interfaces induces interfacial polarization loss,which is confirmed by the density functional theory calculations.Further permeability analysis and the micromagnetic simulation indicate that the nanoscale chiral magnetic heterostructures achieve magnetic pinning and coupling effects,which enhance the magnetic anisotropy and magnetic loss capability.Owing to the synergistic effect between dielectricity,chirality,and magnetism,the trinity composite foam exhibits excellent microwave absorption performance with an ultrabroad effective absorption bandwidth(EAB)of 14 GHz and a minimum reflection of loss less than-50 dB.More importantly,the C-band EAB of the foam is extended to 4 GHz,achieving the full C-band coverage.This study provides further guidelines for the microstructure design of the chiral-dielectric-magnetic trinity composites to achieve broadband microwave absorption.展开更多
This study aims to discuss the propagation characteristics of seismic Lamb wave and surface wave in a new radial gradient supercell seismic metamaterial(RGSSM).Different from the traditional seismic metamaterials with...This study aims to discuss the propagation characteristics of seismic Lamb wave and surface wave in a new radial gradient supercell seismic metamaterial(RGSSM).Different from the traditional seismic metamaterials with simple unit cells,the RGSSM consists of the supercells arranged periodically along the radial direction,and these supercells are composed of five kinds of unit cells with gradient filling rates.The dispersion curve and attenuation spectrum of the Lamb wave in RGSSM are studied with the finite element method combined with the supercell technology,generating a very low-frequency ultra-wide bandgap of 3.98-20 Hz,and a forbidden band generated by the localized modes forms multi-harmonic oscillators inside the supercell.Furthermore,it is found that the Young’s modulus of the soil is more sensitive to the effect of bandgap.In terms of surface wave,the RGSSM can produce rapid attenuation in the low frequency range of 5.2-8.5 Hz.Finally,a 3D model is designed to demonstrate the shielding performance of RGSSM against the seismic surface wave.The proposed RGSSM provides a new idea for the seismic isolation of ultra-wide and low-frequency seismic waves.展开更多
基金supported by the Basic Research Development Program of China(No.JCKY2021607B036)the National Natural Science Foundation of China(No.52275512).
文摘There is an urgent need for the application of broadband Microwave Absorption(MA)structures on the leading edges of aircraft wings,which requires the MA structures to possess both the broadband MA performance and great surface conformability.To meet these requirements,we designed and fabricated a flexible bioinspired meta-structure with ultra-broadband MA,thin thickness and excellent surface conformality.The carbonyl iron powder-carbon nanotubes-polydimethylsiloxane composite was synthesized by physical blending method for fabricating the MA meta-structure.Through geometry-electromagnetic optimal design by heuristic optimization algorithm,the meta-structure mimicking to the nipple photonic nanostructures on the eyes of moth can achieve ultra-broadband MA performance of 35.14 GHz MA bandwidth(reflection loss≤–10 dB),covering 4.86–40.00 GHz,with thickness of only 4.3 mm.Through simple fabrication processes,the meta-structure has been successfully fabricated and bonded on wings’leading edges,exhibiting excellent surface conformability.Furthermore,the designed flexible MA meta-structure possesses significant Radar Cross-Section(RCS)reduction capability,as demonstrated by the RCS analysis of an unmanned aerial vehicle.This flexible ultra-broadband MA meta-structure provides an outstanding candidate to meet the radar stealth requirement of variable curvature structures on aircraft.
基金supported by the National Natural Science Foundation of China(Grant Nos.52192610 and 52192613)the National Key R&D Project from the Minister of Science and Technology(No.2021YFA1201601)the CAS-TWAS President’s Fellow-ship(A.B).
文摘β-Ga_(2)O_(3),as one of the important 4th generation semiconductors,is widely used in solar-blind ultraviolet(UV)detectors with a short detection range of 200-280 nm benefiting from its ultra-wide bandgap,strong radiation resistance,and excellent chemical and thermal stabilities.Here,a self-powered photodetector(PD)based on an Ag/β-Ga_(2)O_(3) Schottky heterojunction was designed and fabricated.Through a subtle design of electrodes,the pyro-phototronic effect was discovered,which can be coupled to the common photovoltaic effect and further enhance the performance of the PD.Compared to traditional Ga_(2)O_(3)-based PD,the as-used PD exhibited a self-driving property and a broadband response beyond the bandgap lim-itations,ranging from 200 nm(deep UV)to 980 nm(infrared).Moreover,the photoresponse time was greatly shrunk owing to the coupling effect.Under laser irradiation,with a wavelength of 450 nm and a power density of 8 mW cm-2,the photocurrent could be improved by around 41 times compared with the sole photovoltaic effect.Besides,the performances of the Schottky PD were enhanced at both high and low temperatures.The device also possessed long-term working stability.This paper not only re-veals basic physics lying in the 4th generation semiconductor Ga_(2)O_(3) but also sheds light on the multi-encryption transmission of light information using this PD.
基金the Deanship of Graduate Studies and Scientific Research at Qassim University for financial support(QU-APC-2024-9/1).
文摘Control signaling is mandatory for the operation and management of all types of communication networks,including the Third Generation Partnership Project(3GPP)mobile broadband networks.However,they consume important and scarce network resources such as bandwidth and processing power.There have been several reports of these control signaling turning into signaling storms halting network operations and causing the respective Telecom companies big financial losses.This paper draws its motivation from such real network disaster incidents attributed to signaling storms.In this paper,we present a thorough survey of the causes,of the signaling storm problems in 3GPP-based mobile broadband networks and discuss in detail their possible solutions and countermeasures.We provide relevant analytical models to help quantify the effect of the potential causes and benefits of their corresponding solutions.Another important contribution of this paper is the comparison of the possible causes and solutions/countermeasures,concerning their effect on several important network aspects such as architecture,additional signaling,fidelity,etc.,in the form of a table.This paper presents an update and an extension of our earlier conference publication.To our knowledge,no similar survey study exists on the subject.
基金National Natural Science Foundation of China (52371171, 52222106, 51971008, 52121001)Fund of National Key Laboratory of Scattering and Radiation (Beijing Institute of Environmental Features)。
文摘[Background and purposes]In recent years,there has been growing attention in academia and industry on the development of high-performance electromagnetic wave(EMW)absorbing materials.However,creating lightweight broadband absorbers remains a challenge in terms of practical applications.EMW absorbing materials primarily rely on the magnetic loss of magnetic materials and/or the dielectric loss of dielectric materials to convert EMW energy into thermal energy for dissipation.Among various magnetic materials,Fe_(3)O_(4) plays an irreplaceable role in EMW absorption due to its high saturation magnetization,low cost and compatible dielectric loss in the gigahertz frequency range.Nevertheless,the high density,large matching thickness and narrow absorption bandwidth of Fe_(3)O_(4) pose significant challenges for practical applications.In contrast,one-dimensional(1D)structures not only retain the characteristic properties of lightweight,chemical stability and high dielectric loss,but also exhibit anisotropic structures and large aspect ratios.Additionally,researchers have found that the minimum reflection loss(RL)of hollow carbon materials with mesopores is nearly four times that of non-porous hollow carbon materials and nine times that of dense carbon materials.According to Maxwell's EMW theory,composites consisting of Fe_(3)O_(4) and one-dimensional(1D)mesoporous carbon materials can leverage their respective advantages by optimizing the composition and structure of the composites to balance u,and Er,thereby enhancing EMW absorption performance.Additionally,numerous studies have demonstrated that composites composed of multi-component heterostructures significantly enhance the EAB.This enhancement is primarily ascribed to the numerous interface polarization losses generated by the additional heterostructure interfaces,which also improve the overall impedance matching of the composites.In this study,we leverage the advantages of magnetic/carbon composites,one-dimensional(1D)mesoporous carbon and multi-component heterostructures to prepare a composite of 1D mesoporous carbon-coated manganese oxide(Mn_(3)O_(4) and MnO,denoted as Mn_(x)O_(y))embedded with Fe_(3)0_(4) nanoparticles(Mn_(x)O_(y)/C@Fe_(3)O_(4)).This composite was synthesized and its formation mechanism and microstructure were analyzed in detail.At the same time,the influence of this Mn_(x)O_(y)/C@Fe_(3)O_(4) structure on EMW properties and absorbing performance was further discussed.[Methods]Firstly,MnO_(2) nanowires were synthesized by using a simple hydrothermal method.Then,the MnO_(2) nanowires served as templates for the synthesis of MnO_(2)/PDA@Fe^(3+)composites through the in-situ polymerization of dopamine and Fe^(3+)adsorption.Finally,1D mesoporous carbon-coated manganese oxide composite embedded with Fe_(3)O_(4) nanoparticles(Mn_(x)O_(y)/C@Fe_(3)O_(4))composites were obtained after heat treatment at 550℃ in N_(2).The crystal structure of the samples was analyzed using X-ray diffractometer with Cu Ka irradiation.Scanning electron microscopy(SEM)and high-resolution transmission electron microscopy(TEM)were used to observe microstructure and morphology of the samples.Nitrogen sorption measurements were obtained at 77 K on a Quantachrome surface area and pore size analyzer to measure the specific surface area and pore size distribution.XPS analysis was performed on X-ray photoelectron spectrometer with monochromatic Al Ka radiation.Magnetization curves of the samples were recorded with a Quantum Design physical property measurement system(PPMS-9)at room temperature.The electromagnetic parameters of the Mn_(x)O_(y)/C@Fe_(3)O_(4) composites were measured using an Agilent N5230C network analyzer in the frequency range of 2-18 GHz.For electromagentic testing,the Mn,Oy/C@Fe34 composites and paraffin wax were mixed at 50°C according to the mass ratio of 15 wt.%,20 wt.%and 25 wt.%,and pressed in a special mold to make coaxial rings(inner diameter=3.04 mm,outer diameter-7 mm),which were denoted as S-1,S-2 and S-3,respectively.[Results]SEM images illustrate the preparation process of iD mesoporous carbon-coated manganese oxide embedded with Fe3O4 nanoparticles composites(Mn_(x)O_(y)/C@Fe_(3)O_(4)).Most of the manganese oxide(Mn,Oy)was reduced to granular after heat treatment,while the outer carbon layer remains its 1D morphology and the carbon layer is interspersed with Fe_(3)O_(4) nanoparticles.The diffraction peaks of MnO_(2) nanowires align well with the body-centered tetragonal a-MnO2.For the Mn_(x)O_(y)/C@Fe_(3)O_(4) composites,the signals of α-MnO_(2) disappears,followed by the emergence of Mn_(3)O_(4) and three prominent diffraction peaks for the cubic MnO.In addition,four weak diffraction peaks correspond to the magnetite Fe_(3)O_(4),consistent with the HRTEM results.The corresponding nitrogen adsorption-desorption isotherm and pore size distribution curve are presented to further analyze the mesoporous structure of composite.The surface composition and element valence states of the Mn_(x)O_(y)/C@Fe_(3)O_(4) composite were investigated by using XPS.The polarization relaxation processes were analyzed according to the Debye theory which describes the relationship between e'and e".Besides the polarization loss,the contribution of the conduction loss plays an important role for the overall dielectric loss.The magnetization curve of Mn_(x)O_(y)/C@Fe_(3)O_(4) exhibits typical ferromagnetic behavior.The permittivity parameter(Co),defined as Co=u"(u)^(-2)f^(-1) determine the contribution of eddy current effect to magnetic loss.The tand values are all larger than those of tand,for the three samples,indicating that the loss capacity of Mn_(x)O_(y)/C@Fe_(3)O_(4) composites is mainly derived from the dielectric loss.Although tand,is smaller,it plays an important role in improving the impedance matching of Mn_(x)O_(y)/C@Fe_(3)O_(4) composites.When the filler loading is 15 wt.%,the RL of sample S-1 is about-10.0 dB at the thickness of 1.5 mm with narrow EAB.As the filler loading increased to 20 wt.%,the RL of sample S-2 reached-62.0 dB at a thickness of 2.2 mm and the EAB was 6.4 GHz at a small thickness of 1.7 mm.When the filler loading is further increased to 25 wt.%,the microwave absorption performance of sample S3 decreased significantly with a little region of RL<-10.0 dB at the thickness of 5.0 mm.The values of[Zin/Zol of the three samples at thicknesses of 1.5-5.0 mm were calculated.Due to good impedance matching of S-2,the incident EMW can enter the material and then can be dissipated through dipole polarization loss,interface polarization loss,conduction loss,eddy current loss and natural ferromagnetic resonance loss.[Conclusions]1D Mn_(x)O_(y)/C@Fe_(3)O_(4) was synthesized via a process involving the coating of polydopamine,adsorption of Fe(ll)salts and heat treatment,using MnO_(2) nanowires as templates.The multi-component heterostructure of the Mn_(x)O_(y)/C@Fe_(3)O_(4) composite(Mn_(3)O_(4),MnO,Fe_(3)O_(4),and C)enhances the interfacial interactions between the different phases,providing increased interface polarization loss under the action of an alternating electromagnetic field.The numerous defects and terminal groups in the mesoporous carbon provide abundant dipole polarization centers.Additionally,the presence of mesopores reduces the weight of the material while increasing the multiple scattering losses of the electromagnetic waves within the material.The ID carbon structure in the matrix forms a conductive network between adjacent fibers,facilitating electron migration and transition,thereby enhancing conductive loss.The incorporation of magnetic Fe_(3)O_(4) nanoparticles introduces eddy current loss and natural ferromagnetic resonance loss,thus increasing magnetic loss.Moreover,the synergistic effect between dielectric and magnetic losses improves the impedance matching of the material,leading to excellent EMW absorption performance.
文摘Broadband near-infrared(NIR)luminescent materials have shown great promise in applications such as optical communication,biomedicine,and optoelectronic devices.However,the current research is focused on phos⁃phors and glasses,and it is important to develop broadband NIR luminescent nanomaterials.Here,we report an erbi⁃um-sensitized core-shell nanocrystal design for broadband NIR emission.Based on the structural design with suitable dopings of Tm^(3+)and Ho^(3+),the broadband NIR emission covering 1.5-2.1μm region is achieved under 980 nm and 808 nm excitations.Moreover,the emission intensity is further enhanced by introducing Yb^(3+)and Nd^(3+)into the sam⁃ple,respectively,and the energy transfer processes between them are systematically discussed.Our results present a novel approach for developing broadband NIR luminescent materials and devices.
基金financially supported by the National Natural Science Foundation of China(Nos.22435005,22193042,21921001,22305105,52202194,22201284)Natural Science Foundation of Jiangxi Province(No.20224BAB213003)+1 种基金the Natural Science Foundation of Fujian Province(No.2023J05076)Jiangxi Provincial Education Department Science and Technology Research Foundation(No.GJJ2200384)。
文摘Two-dimensional perovskite ferroelectric which strongly couple ferroelectricity with semiconducting properties are promising candidates for optoelectronic applications.However,it is still a great challenge to fabricate self-powered broadband photodetectors with low detection limit.Herein,we successfully realized self-powered broadband photodetection with low detection limit by using a trilayered perovskite ferroelectric(BA)_(2)EA_(2)Pb_(3)I_(10)(1,BA=n-butylamine,EA=ethylamine).Giving to its large spontaneous polarization(5.6μC/cm^(2)),1 exhibits an open-circuit voltage of 0.25 V which provide driving force to separate carriers.Combining with its low dark current(~10^(-14)A)and narrow bandgap(Eg=1.86 e V),1 demonstrates great potential on detecting the broadband weak lights.Thus,a prominent photodetection performance with high open-off ratio(~10^(5)),outstanding responsivity(>10 m A/W),and promising detectivity(>1011Jones),as well as the low detecting limit(~nW/cm^(2))among the wide wavelength from 377 nm to637 nm was realized based on the single crystal of 1.This work demonstrates the great potential of 2D perovskite ferroelectric on self-powered broadband photodetectors.
基金financially supported by the National Natural Science Foundation of China(Nos.22005183 and 22275117)the Program of State Key Laboratory of Quantum Optics and Quantum Optics Devices(No.KF202204)。
文摘Dion-Jacobson (DJ) phase hybrid perovskites have been proven to improve the photovoltaic performance of the devices due to its unique structure.At present,some DJ hybrid perovskites have been reported and used for photodetection filed,but most of them are based on lead-bromide systems,which is not conducive to construct broadband photodetection devices due to the limitation of intrinsic absorption.Herein,we constructed a bilayered DJ hybrid perovskite (3AMPY)(EA)Pb_(2)I_(7)(3AMPY^(2+)is 3-(aminomethyl)pyridinium,EA^(+)is ethylammonium) using an aromatic spacer,which exhibit large current on/off ratios of 10~4under 520 and 637 nm illumination.In particular,the single crystal device based on (3AMPY)(EA)Pb_(2)I_(7)shows a distinguished detectivity of 7.4×10^(12)Jones and a high responsivity of 0.89A/W under 637 nm illumination.Such finding not only enriches the quantities of DJ hybrid perovskites,but also provides useful assistance for constructing high-performance optoelectronic device in the future.
基金support by the Advanced Integrated Optoelectronics Facility at Tianjin University
文摘Metasurfaces composed of two-dimensional nanopillar arrays can manipulate light fields in desirable ways and exhibit the unique advantage of beam steering.Here,we experimentally demonstrate a metasurface-based wide-angle broadband all-dielectric blazed grating with an extreme incident angle of up to 80°,which is achieved by optimizing the wide-angle phase shifts and transmissivities of the unit cells.It exhibits a maximum diffraction efficiency of 72%and a high average efficiency of 64%over a wide range of incident angles from−80° to 45° at 1.55μm.Moreover,the proposed grating has a broad bandwidth of 200 nm(1.45-1.65μm),and average efficiencies of more than 50%can be achieved experimentally over the same incidence angles.Our results may pave the way for the creation of novel and efficient flat optical devices for wavefront control.
基金the support form the National Natural Science Foundation of China(Grant Nos.51606158,11604311,12074151)the Funded by the Guangxi Science and Technology Base and Talent Special Project(Grant No.AD21075009)+3 种基金the funded by the Sichuan Science and Technology Program(Grant No.2021JDRC0022)the Open Fund of the Key Laboratory for Metallurgical Equipment and Control Technology of Ministry of Education in Wuhan University of Science and Technology,China(Grant Nos.MECOF2022B01MECOF2023B04)the Project supported by Guangxi Key Laboratory of Precision Navigation Technology and Application,Guilin University of Electronic Technology(Grant No.DH202321)。
文摘This paper presents a tunable and polarization-insensitive wideband metamaterial absorber based on single-layer graphene.By comparing the simulated experimental data with theoretical derivations,it was found that the absorbance of the material can be sustained above 90%in the frequency range of 2.78 to 7.14(4.36)THz,of which the absorption rate exceeds 99%in the frequency range of 4.1–4.54(0.44)THz,and remarkably,perfect absorption is achieved at4.32 THz.In the range of 2.78–7.14 THz,the average absorption rate is 96.1%,by adjusting the physical size of the graphene layer pattern,we can modify the working band gap of the absorber.By applying a voltage to modulate the Fermi level of graphene,we can increase the absorption bandwidth.When the chemical potential is 1.0 e V,at the bandwidth of 4.36 THz,its absorption rate exceeds 90%.The working principle of absorbing materials was deeply explored using the principles of electromagnetic field distribution and impedance adaptation.Through detailed analysis of different polarization states and incident angles,we found that the absorber is not sensitive to polarization due to its symmetrical structure,and found that it exhibits low sensitivity at incidence angles.In addition,after comparative analysis,significant differences were observed in the absorption efficiency of the absorber under various relaxation time conditions,and the obtained data were elaborated in detail using the carrier mechanism of plasma vibration.We found that in addition to obtaining an almost perfect absorber with wide band by adjusting the parameters,it is also feasible to obtain an approximately narrow band absorber by changing the relaxation time without having to remanufacture the structure.The absorber offers several advantages,including tunability,a wide absorption band,a high absorption rate,polarization insensitivity,and a simple structure.Therefore,this absorber exhibits great potential for absorption,monitoring,and sensing in the terahertz band.
基金Project supported by the National Key Research and Development Program of China(Grant No.2021YFB2012600)the Science and Technology Plan Project of the State Administration of Market Regulation,China(Grant No.2021MK039)the Suqian Talent Elite Program(Grant No.SQQN202414)。
文摘This paper presents a compact broadband antenna that overcomes bandwidth limitations in a diamond nitrogenvacancy(NV)center-based quantum magnetic sensor.Conventional antennas struggle to achieve both broadband operation and compact integration,restricting the sensitivity and dynamic range of the sensor.The broadband antenna based on a dualfrequency monopole structure achieves a bandwidth extension of 777 MHz at the Zeeman splitting frequency of 2.87 GHz,with the dual resonant points positioned near 2.87 GHz.Additionally,high-resolution imaging of the microwave magnetic field on the antenna surface was performed using a diamond optical fiber probe,which verified the dual-frequency design principle.Experimental results using the proposed antenna demonstrate the outstanding performance of the NV centerbased magnetic sensor:a sensitivity of 55 nT/Hz^(1/2)and a dynamic range of up to 54.0 dB.Compared to sensors using conventional antennas,the performance has been significantly improved.
基金supported by the National Natural Science Foundation of China(Nos.T2325005,62375016,62475250)the Science and Technology Project of Guangdong(No.2020B010190001)。
文摘A polarization converter with broadband polarization characteristics and capable of dynamic reconfiguration is proposed.By introducing out-of-plane degrees of freedom,dynamically tunable broadband and high-efficiency linear polarization conversion within the wavelength range of 2000-2800 nm is achieved.Research results indicate that when a two-dimensional(2D)split-ring resonator(SRR)is irradiated by a low-dose focused ion beam,it will deform upward and transform into a three-dimensional(3D)SRR,achieving a linear polarization conversion efficiency of over 90%.The 3D SRR can be driven by electrostatic force to return to the 2D SRR state,thereby realizing the dynamic reconfiguration of this polarization converter.By changing the applied voltage and adjusting the structural parameters,a tailored polarization converter that exhibits broadband performance and high polarization conversion efficiency is also achieved.The results may provide novel ideas and technical methodologies for various applications such as polarized optical imaging,emerging display technologies,polarized optical communication,and optical sensing.
文摘The performance breakthroughs of some stealth materials have benefited from incorporating biomimetic concepts,and the design ideas of wave-absorbing metamaterials have been greatly broadened.How-ever,stealth materials developed based on a single biological structure still have limitations regarding overall performance and design freedom.Herein,a dual-structure element combination model with a butterfly-wing porous structure and moth-eye raised structure arranged in an orderly manner is estab-lished.Carbonyl iron and polyurethane are mixed as wave absorbents,and the model is utilized to make a biomimetic metamaterial(CSMA),which has an absorption rate of more than 90%at 6.07-18 GHz,achieving broadband effective absorption.It has been verified that the two biostructures designed after an ordered arrangement show synergistic effects in the combined model,and the cooperation between the structures induces the formation of current vector vortices,which are able to induce microwave losses to broaden the effective absorbing bandwidth.Further,the model has the combined application performance of polarization insensitivity,strong stability of oblique incidence,and low bistatic RCS.Such a thought based on the combination of multiple components provides an effective strategy for the design of broadband-absorbing metamaterials.
基金the support from the National Key Research and Development Program of China(2022YFB2803900 and 2018YFA0704403)NSFC(62074064)。
文摘Full-Stokes polarimeters can detect the polarization states of light,which is critical for the next-generation optical and optoelectronic systems.Traditional full-Stokes polarimeters are either based on bulky optical systems or complex metasurface structures,which cause the system complexity with unessential energy loss.Recently,filterless on-chip full-Stokes polarimeters have been demonstrated by using optical anisotropic materials which are able to detect the circularly polarized light.Nevertheless,those on-chip full-Stokes polarimeters have either the limited detection wavelength range or relatively poor device performance that need to be further improved.Here,we report the high performance broadband full-Stokes polarimeters based on rhenium disulfide(ReS_(2)).While the anisotropic structure of the ReS_(2)introduces the in-plane optical anisotropy for linearly polarized light(LP)detection,Schottky contacts formed by the ReS_(2)-Au could break the symmetry,which can detect circularly polarized(CP)light.By building a proper model,all four Stokes parameters can be extracted by using the ReS_(2)nanobelt device.The device delivers a photoresponsivity of 181 A/W,a detectivity of 6.8×10^(10)Jones and can sense the four Stokes parameters of incident light within a wide range of wavelength from 565-800 nm with reasonable average errors.We believe our study provides an alternative strategy to develop high performance broadband on-chip full-Stokes polarimeters.
基金supported by the Innovation Program for Quantum Science and Technology(Grant No.2023ZD0301000)the Chongqing Technology Innovation and Application Develop-ment Project(Grant No.CSTB2022TIAD-DEX0031).
文摘Tunable mid-infrared lasers are essential for optical sensing and imaging.Existing technologies,however,face challenges in simultaneously achieving broadband spectral tunability and ultra-rapid scan rates,limiting their utility in dynamic scenarios such as real-time characterization of multiple molecular absorption bands.We present a high-speed approach for broadband wavelength sweeping in the mid-infrared region,leveraging spectral focusing via difference-frequency generation between a chirped fiber laser and an asynchronous,frequency-modulated electro-optic comb.This method enables pulse-to-pulse spectral tuning at a speed of 5.6 THz∕μs with 380 elements.Applied to spectroscopic sensing,our technique achieves broad spectral coverage(2600 to 3780 cm−1)with moderate spectral resolution(8 cm−1)and rapid acquisition time(-6.3μs).Notably,the controllable electro-optic comb facilitates high scan rates of up to 2 Mscans∕s across the full spectral range(corresponding to a speed of 60 THz∕μs),with trade-offs in number of elements(-30)and spectral point spacing or resolution(33 cm−1).Nevertheless,these capabilities make our platform highly promising for applications such as flow cytometry,chemical reaction monitoring,and mid-infrared ranging and imaging.
基金the National Natural Science Foundation of China(Nos.22275096,W2432015)Natural Science Key Fund for Universities in Jiangsu Province(No.22KJA430007)Qinglan Project of Jiangsu Province of China。
文摘Broadband photothermal and photoacoustic agents in the near-infrared(NIR)biowindow are of significance for cancer phototheranostics.In this work,Pt Cu nanosheets with an average lateral size of less than 10 nm are synthesized as NIR photothermal and photoacoustic agents in vivo,which show strong light absorption from NIR-I to NIR-II biowindows with the photothermal conversion efficiencies of 20.4%under 808 nm laser and 32.7%under 1064 nm laser.Pt Cu nanosheets functionalized with folic acidmodified thiol-poly(ethylene glycol)(SH-PEG-FA)present good biocompatibility and 4T1 tumor-targeted effect,which give high-contrast photoacoustic imaging and efficient photothermal ablation of 4T1 tumor in both NIR-I and NIR-II biowindows.Our work significantly broadens applications of noble metal-based nanomaterials in the fields of cancer phototheranostics by rationally designing their structures and modulating their physicochemical properties.
基金supported by the National Natural Science Foundation of China(No.22265021)the Aeronautical Science Foundation of China(No.2020Z056056003)。
文摘Considering the challenges posed by severe electromagnetic wave pollution and escalating international tensions,there is a critical need to develop advanced electromagnetic wave absorbing(EMWA)materials that integrate radar stealth and thermal insulation capabilities.In this study,we have synthesized three-dimensional(3D)porous composites comprising V_(2)O_(3) nanoparticles embedded in Juncus effusus cellulose-derived carbon aerogels(VCA)using a self-templating method followed by high-temperature pyrolysis.The V_(2)O_(3) nanoparticles possess a 3D V-V framework and a relatively narrow bandgap,facilitating the Mott transition for enhanced conductivity.Furthermore,their uniform dispersion on hollow carbon tubes of Juncus effusus promotes efficient electron transfer and creates numerous heterogeneous interfaces.Consequently,VCA-2 demonstrates outstanding EMWA performance,achieving a minimum reflection loss of−63.92 dB at a matching thickness of 2.0mm and a maximum effective absorption bandwidth of 8.24 GHz at a thickness of 2.44mm,covering nearly half of the tested frequency range.Additionally,the radar cross-section reduction reaches a peak value of 29.40 dB m^(2),underscoring the excellent radar stealth capabilities of the material.In summary,VCA exhibits exceptional EMWA,radar stealth,and thermal insulation properties,highlighting its potential for multifunctional applications in EMWA material development.
基金supported by the National Key R&D Program of China (Grant Nos. 2023YFC3010703, 2020YFB1708800, and 2023YFC3010705)。
文摘Optically transparent microwave absorbers and multi-band stealth have extensive potential applications in military defense and wireless communication fields, and thus have attracted considerable attention. So far,most related work is based on inorganic transparent conductive metasurfaces. In this paper, we proposed and experimentally demonstrated a flexible, broadband and optically transparent microwave absorber using an organic metasurface. The metasurface absorber is composed of a sandwich structure, in which electric resonances and magnetic resonances are induced resulting in broadband absorption. A spraying process was developed to prepare this metasurface absorber. Both simulations and experiment show that this metasurface has broadband microwave absorption and good optical transparency. We further found that by using a multi-layer structure, visible, radar,and infrared stealth(multi-band stealth) can be achieved simultaneously. With the advantages of excellent foldability and low cost, the proposed metasurfaces may have applications in military and wireless communication fields.
基金supported by the Fundamental Research Funds for the Central Universities (No.2024JBZY021)the National Natural Science Foundation of China (No.61575018)。
文摘Reverse design of highly GeO2-doped silica optical fibers with broadband and flat dispersion profiles is proposed using a neural network(NN) combined with a particle swarm optimization(PSO) algorithm.Firstly,the NN model designed to predict optical fiber dispersion is trained with an appropriate choice of hyperparameters,achieving a root mean square error(RMSE) of 9.47×10-7on the test dataset,with a determination coefficient(R2) of 0.999.Secondly,the NN is combined with the PSO algorithm for the inverse design of dispersion-flattened optical fibers.To expand the search space and avoid particles becoming trapped in local optimal solutions,the PSO algorithm incorporates adaptive inertia weight updating and a simulated annealing algorithm.Finally,by using a suitable fitness function,the designed fibers exhibit flat group velocity dispersion(GVD) profiles at 1 400—2 400 nm,where the GVD fluctuations and minimum absolute GVD values are below 18 ps·nm-1·km-1and 7 ps·nm-1·km-1,respectively.
基金supported by the National Natural Science Foundation of China[Grant Nos.52272288 and 51972039]the China Postdoctoral Science Foundation[No.2021M700658].
文摘The construction of carbon nanocoil(CNC)-based chiral-dielectric-magnetic trinity composites is considered as a promising approach to achieve excellent low-frequency microwave absorption.However,it is still challenging to further enhance the low frequency microwave absorption and elucidate the related loss mechanisms.Herein,the chiral CNCs are first synthesized on a threedimensional(3D)carbon foam and then combined with the FeNi/NiFe_(2)O_(4) nanoparticles to form a novel chiral-dielectric-magnetic trinity foam.The 3D porous CNC-carbon foam network provides excellent impedance matching and strong conduction loss.The formation of the FeNi-carbon interfaces induces interfacial polarization loss,which is confirmed by the density functional theory calculations.Further permeability analysis and the micromagnetic simulation indicate that the nanoscale chiral magnetic heterostructures achieve magnetic pinning and coupling effects,which enhance the magnetic anisotropy and magnetic loss capability.Owing to the synergistic effect between dielectricity,chirality,and magnetism,the trinity composite foam exhibits excellent microwave absorption performance with an ultrabroad effective absorption bandwidth(EAB)of 14 GHz and a minimum reflection of loss less than-50 dB.More importantly,the C-band EAB of the foam is extended to 4 GHz,achieving the full C-band coverage.This study provides further guidelines for the microstructure design of the chiral-dielectric-magnetic trinity composites to achieve broadband microwave absorption.
文摘This study aims to discuss the propagation characteristics of seismic Lamb wave and surface wave in a new radial gradient supercell seismic metamaterial(RGSSM).Different from the traditional seismic metamaterials with simple unit cells,the RGSSM consists of the supercells arranged periodically along the radial direction,and these supercells are composed of five kinds of unit cells with gradient filling rates.The dispersion curve and attenuation spectrum of the Lamb wave in RGSSM are studied with the finite element method combined with the supercell technology,generating a very low-frequency ultra-wide bandgap of 3.98-20 Hz,and a forbidden band generated by the localized modes forms multi-harmonic oscillators inside the supercell.Furthermore,it is found that the Young’s modulus of the soil is more sensitive to the effect of bandgap.In terms of surface wave,the RGSSM can produce rapid attenuation in the low frequency range of 5.2-8.5 Hz.Finally,a 3D model is designed to demonstrate the shielding performance of RGSSM against the seismic surface wave.The proposed RGSSM provides a new idea for the seismic isolation of ultra-wide and low-frequency seismic waves.
