Terahertz biotechnology has been increasingly applied in various biomedical fields and has especially shown great potential for application in brain sciences.In this article,we review the development of terahertz biot...Terahertz biotechnology has been increasingly applied in various biomedical fields and has especially shown great potential for application in brain sciences.In this article,we review the development of terahertz biotechnology and its applications in the field of neuropsychiatry.Available evidence indicates promising prospects for the use of terahertz spectroscopy and terahertz imaging techniques in the diagnosis of amyloid disease,cerebrovascular disease,glioma,psychiatric disease,traumatic brain injury,and myelin deficit.In vitro and animal experiments have also demonstrated the potential therapeutic value of terahertz technology in some neuropsychiatric diseases.Although the precise underlying mechanism of the interactions between terahertz electromagnetic waves and the biosystem is not yet fully understood,the research progress in this field shows great potential for biomedical noninvasive diagnostic and therapeutic applications.However,the biosafety of terahertz radiation requires further exploration regarding its two-sided efficacy in practical applications.This review demonstrates that terahertz biotechnology has the potential to be a promising method in the field of neuropsychiatry based on its unique advantages.展开更多
Strong-field terahertz waves not only have high peak power but also possess strong electromagnetic field components.When electrons encounters strong-field terahertz waves,a series of novel changes are induced,which ha...Strong-field terahertz waves not only have high peak power but also possess strong electromagnetic field components.When electrons encounters strong-field terahertz waves,a series of novel changes are induced,which have attracted extensive attention.This review first introduces common optical sources for strong-field terahertz emission,such as photoconductive antennas,optical rectification crystals,and air plasmas.Subsequently,recent applications of strong-field terahertz technology in material state modulation are presented,mainly including strong-field terahertz wave-driven hot carrier motion,coherent phonon control,spintronics,electron acceleration,and biomedicine.展开更多
In this paper,a terahertz slotted waveguide array antenna is designed based on photonic crystal,which can realize efficient radiation of terahertz waves.The electromagnetic wave is fed from the rectangular waveguide a...In this paper,a terahertz slotted waveguide array antenna is designed based on photonic crystal,which can realize efficient radiation of terahertz waves.The electromagnetic wave is fed from the rectangular waveguide at the bottom of the antenna,coupled to photonic crystal waveguide through photonic crystal cavity,and radiated outward through slots at the top layer of antenna.The simulation results show that the antenna achieves a peak gain of 13.45 dBi at 360 GHz,a half-power beam width of 10.9°,and a side lobe level of−13.9 dB.The antenna based on photonic crystal has the advantages of low profile,low loss,and high radiation efficiency,which can be applied to terahertz wireless communication systems.展开更多
Strong-field terahertz(THz) radiation holds significant potential in non-equilibrium state manipulation, electron acceleration, and biomedical effects. However, distortion-free detection of strong-field THz waveforms ...Strong-field terahertz(THz) radiation holds significant potential in non-equilibrium state manipulation, electron acceleration, and biomedical effects. However, distortion-free detection of strong-field THz waveforms remains an essential challenge in THz science and technology. To address this issue, we propose a ferromagnetic detection scheme based on Zeeman torque sampling, achieving distortion-free strong-field THz waveform detection in Py films. Thickness-dependent characterization(3–21 nm) identifies peak detection performance at 21 nm within the investigated range. Furthermore, by structurally engineering the Py ferromagnetic layer, we demonstrate strong-field THz detection in symmetric Ta(3 nm)/Py(9 nm)/Ta(3 nm) heterostructure while simultaneously resolving Zeeman torque responses and collective spin-wave dynamics in asymmetric W(4 nm)/Py(9 nm)/Pt(2 nm)heterostructure. We calculated spin wave excitations and spin orbit torque distributions in asymmetric heterostructures, along with spin wave excitations in symmetric modes. This approach overcomes the sensitivity limitations of conventional techniques in strong-field conditions.展开更多
High-performance terahertz(THz)logic gate devices are crucial components for signal processing and modulation,playing a significant role in the application of THz communication and imaging.Here,we propose a THz broadb...High-performance terahertz(THz)logic gate devices are crucial components for signal processing and modulation,playing a significant role in the application of THz communication and imaging.Here,we propose a THz broadband NOR logic encoder based on a graphene-metal hybrid metasurface.The unit structure consists of two symmetrical dual-gap metal split-ring resonators(DSRRs)arranged in a staggered configuration,with graphene strips embedded in their gaps.The NOR logic gate metadevice is controlled by the bias voltages independently applied to the two electrodes.Experiments show that when the bias voltages are applied to both electrodes,the metadevice achieves the NOR logic gate within a 0.52 THz bandwidth,with an average modulation depth above 80%.The experimental results match well with theoretical simulations.Additionally,the strong near-field coupling induced by the staggered DSRRs causes redshift at both LC resonance and dipole resonance.This phenomenon was demonstrated by coupled mode theory.Besides,we analyze the surface current distribution at resonances and propose four equivalent circuit models to elucidate the physical mechanisms of modulation under distinct loaded voltage conditions.The results not only advance modulation and logic gate designs for THz communication but also demonstrate significant potential applications in 6G networks,THz imaging,and radar systems.展开更多
The research on two-dimensional(2D)magnetic materials and their heterostructures is crucial in fields like spintronics,materials science,and condensed matter physics.This study uses terahertz(THz)time-domain spectrosc...The research on two-dimensional(2D)magnetic materials and their heterostructures is crucial in fields like spintronics,materials science,and condensed matter physics.This study uses terahertz(THz)time-domain spectroscopy to investigate ultrafast electron transport properties in both van der Waals Fe_(4)GeTe_(2)films and Bi_(2)Te_(3)/Fe_(4)GeTe_(2)ferromagnetic/topological heterostructures.Our results show that these heterostructures exhibit effective THz electromagnetic shielding.The complex conductivity spectra of Fe_(4)GeTe_(2)films and Bi_(2)Te_(3)/Fe_(4)GeTe_(2)heterostructures with varying Fe_(4)GeTe_(2)thicknesses are analyzed using the Drude-Smith model.We quantitatively examine how Fe_(4)GeTe_(2)layer thickness affects the direct current conductivity,plasma frequency,carrier momentum scattering time,and back-scattering coefficient.As the number of Fe_(4)GeTe_(2)layers increases,intra-layer back-scattering events for charge carriers become more frequent.This work provides THz frequency spectra for both Fe_(4)GeTe_(2)and Bi_(2)Te_(3)/Fe_(4)GeTe_(2),aiding in the design and optimization of THz modulators and detectors.展开更多
With the explosion of wireless data rates,the terahertz(THz)band(0.1–10 THz)is envisioned as a promising candidate to break the existing bandwidth bottleneck and satisfy the ever-increasing capacity demand.The THz wi...With the explosion of wireless data rates,the terahertz(THz)band(0.1–10 THz)is envisioned as a promising candidate to break the existing bandwidth bottleneck and satisfy the ever-increasing capacity demand.The THz wireless communications feature a number of attractive properties,such as potential terabit-per-second capacity and high energy efficiency.In this paper,an overview on the state-of-the-art THz communications is studied,with a special focus on key technologies of THz transceivers and THz communication systems.The recent progress on both electronic and photonic THz transmitters are presented,and then the THz receivers operating in direct-and heterodyne reception modes are individually surveyed.Based on the THz transceiver schemes,three kinds of THz wireless communication systems are reviewed,including solid-state electronic systems,photonics-assisted systems and all-photonics systems.The prospective key enabling technologies,corresponding challenges and research directions for lighting up high-speed THz communication systems are discussed as well.展开更多
Fibroblasts support a broad range of essential organ functions via microarchitectural,biomechanical,and biochemical cues.Despite great advances in fluorescence,photoacoustic conversion,and Raman scattering over the pa...Fibroblasts support a broad range of essential organ functions via microarchitectural,biomechanical,and biochemical cues.Despite great advances in fluorescence,photoacoustic conversion,and Raman scattering over the past decades,their invasiveness and limited spatial resolution hinder the characterization of fibroblasts in a single cell.Here,taking mouse embryonic fibroblasts(MEFs)as an example,we propose a novel noninvasive approach to investigate the compositional distribution of MEFs at the single-cell scale via terahertz(THz)nanos⁃copy.Compared to the topological morphology,THz nano-imaging enables the component-based visualization of MEFs,such as the membrane,cytoplasm,nucleus,and extracellular vesicles(EVs).Notably,we demonstrate the real-space observation of the influence of rapamycin treatment on the increase of EVs in MEFs.Moreover,the line-cut and area-statistical analysis establishes the relationship between the topological morphology and the THz near-field amplitudes for different cellular components of MEFs.This work provides a new pathway to char⁃acterize the effects of pharmaceutical treatments,with potential applications in disease diagnosis and drug devel⁃opment.展开更多
Enamel demineralization often occurs in the early stage of dental caries.Studying the microscopic mechanism of enamel demineralization is essential to prevent and treat dental caries.Terahertz(THz)technolo⁃gy,especial...Enamel demineralization often occurs in the early stage of dental caries.Studying the microscopic mechanism of enamel demineralization is essential to prevent and treat dental caries.Terahertz(THz)technolo⁃gy,especially continuous wave(CW)THz near-field scanning microscopy(THz-SNOM)with its nanoscale reso⁃lution,can be promising in biomedical imaging.In addition,compared with traditional THz time-domain spec⁃troscopy(TDS),portable solid-state source as the emission has higher power and SNR,lower cost,and can ob⁃tain more precise imaging.In this study,we employ CW THz-SNOM to further break the resolution limitations of conventional THz imaging techniques and successfully achieve the near-field imaging of demineralized enamel at the nanoscale.We keenly observe that the near-field signal of the enamel significantly lowers as demineralization deepens,mainly due to the decrease in permittivity.This new approach offers valuable insights into the micro⁃scopic processes of enamel demineralization,laying the foundation for further research and treatment.展开更多
Compared to traditional single-frequency bound states in the continuum(BIC),dual-band BIC of-fers higher degrees of freedom and functionality.Moveover,implementing independent control of dual-band BICs can further enh...Compared to traditional single-frequency bound states in the continuum(BIC),dual-band BIC of-fers higher degrees of freedom and functionality.Moveover,implementing independent control of dual-band BICs can further enhance their advantages and maximize their performance.This study presents a design for a dielectric metasurface that achieves dual-band BICs in the terahertz(THz)range.By adjusting two asym-metry parameters of the structure,independent control of the two symmetry-protected BICs is achieved.Fur-thermore,by varying the shape of the silicon holes,the design's robustness to geometric variations is demon-strated.Finally,the test results show that the figures of merit(FOMs)for both BICs reach 109.This work provides a new approach for realizing and tuning dual-frequency BICs,offering expanded possibilities for applications in multimode lasers,nonlinear optics,multi-channel filtering,and optical sensing.展开更多
To address the issues of peak overlap caused by complex matrices in agricultural product terahertz(THz)spectral signals and the dynamic,nonlinear interference induced by environmental and system noise,this study explo...To address the issues of peak overlap caused by complex matrices in agricultural product terahertz(THz)spectral signals and the dynamic,nonlinear interference induced by environmental and system noise,this study explores the feasibility of adaptive-signal-decomposition-based denoising methods to improve THz spectral quality.THz time-domain spectroscopy(THz-TDS)combined with an attenuated total reflection(ATR)accessory was used to collect THz absorbance spectra from 48 peanut samples.Taking the quantitative prediction model of peanut moisture content based on THz-ATR as an example,wavelet transform(WT),empirical mode decomposition(EMD),local mean decomposition(LMD),and its improved methods-segmented local mean decomposition(SLMD)and piecewise mirror extension local mean decomposition(PME-LMD)-were employed for spectral denoising.The applicability of different denoising methods was evaluated using a support vector regression(SVR)model.Experimental results show that the peanut moisture content prediction model constructed after PME-LMD denoising achieved the best performance,with a root mean square error(RMSE),coefficient of determination(R^(2)),and mean absolute percentage error(MAPE)of 0.010,0.912,and 0.040,respectively.Compared with traditional methods,PME-LMD significantly improved spectral quality and model prediction performance.The PME-LMD denoising strategy proposed in this study effectively suppresses non-uniform noise interference in THz spectral signals,providing an efficient and accurate preprocessing method for THz spectral analysis of agricultural products.This research provides theoretical support and technical guidance for the application of THz technology for detecting agricultural product quality.展开更多
The terahertz time-domain spectroscopy （THz-TDS） system and the related technology and the applications in Capital Normal University are presented. The most often used THz-TDS system as a spectroscopic measurement ...The terahertz time-domain spectroscopy （THz-TDS） system and the related technology and the applications in Capital Normal University are presented. The most often used THz-TDS system as a spectroscopic measurement setup in our lab is introduced in detail, including the THz radiation source, the THz detection method and its measurement, and the control system. THz spectra of various materials is summarized and discussed. These materials include but not limited to two kinds of typical matter-the illegal drugs and explosives. The biological macro-molecules, cosmetics and fine chemical materials, edible pigments and food additives, homocysteic acid and related compounds, heavy ions in soil, Chinese medicines, tobacco and crops, oil and chemical products, carbon nanotubes, superconductors, and various semiconductors and their heterojunctions, are presented. THz emissions from the InAs and InN semiconductors surface are compared. THz spectral investigation of metallic mesh structures is summarized. Finally, an outlook of THz spectroscopic applications is given.展开更多
Resonant linear and nonlinear properties in terahertz range of 2D materials graphene and silicene placed into a bias magnetic field are investigated theoretically on the base of the quasi-classical kinetic theory. Whe...Resonant linear and nonlinear properties in terahertz range of 2D materials graphene and silicene placed into a bias magnetic field are investigated theoretically on the base of the quasi-classical kinetic theory. When the electromagnetic frequency is close to the cyclotron one, the linear conductivity increases two orders. Under the resonant frequencies nonlinearity becomes essential at low magnitudes of terahertz electric fields. In absence of a bias magnetic field the nonlinear dependences of the surface electric currents on terahertz electric field are practically the same simulated from kinetics and electron hydrodynamics with nonzero “kinetic” electron effective mass. Graphene possesses higher values of nonlinearity of the resonant conductivity, whereas in absence of a bias magnetic field, the electron nonlinearity is higher in silicene.展开更多
With the urgently increasing demand for high-speed and large-capacity communication trans-mission,there remains a critical need for tunable terahertz(THz)devices with multi-channel in 5G/6G communication systems.A mag...With the urgently increasing demand for high-speed and large-capacity communication trans-mission,there remains a critical need for tunable terahertz(THz)devices with multi-channel in 5G/6G communication systems.A magnetic phase-coding meta-atom(MPM)is formed by the heterogeneous integration of La:YIG magneto-optical(MO)materials and Si microstructures.The MPM couples the magnetic induction phase of spin states with the propagation phase and can simultaneously satisfy the required output phase for dual frequencies under various external magnetic fields to realize the dynamic beam steering among multiple channels at 0.25 and 0.5 THz.The energy ratio of the target direction can reach 96.5%,and the nonreciprocal one-way transmission with a max isolation of 29.8 dB is realized due to the nonreciprocal phase shift of the MO layer.This nonreciprocal mechanism of magnetic induction reshaping of wavefront significantly holds promise for advancing integrated multi-functional THz devices with the characteristics of low-crosstalk,multi-channel,and multi-frequency,and has great potential to promote the development of THz large-capacity and high-speed communication.展开更多
Terahertz(THz)devices,owing to their distinctive optical properties,have achieved myriad applications in diverse domains including wireless communication,medical imaging therapy,hazardous substance detection,and envir...Terahertz(THz)devices,owing to their distinctive optical properties,have achieved myriad applications in diverse domains including wireless communication,medical imaging therapy,hazardous substance detection,and environmental governance.Concurrently,to mitigate the environmental impact of electronic waste generated by traditional materials,sustainable materialsbased THz functional devices are being explored for further research by taking advantages of their eco-friendliness,cost-effective,enhanced safety,robust biodegradability and biocompatibility.This review focuses on the origins and distinctive biological structures of sustainable materials as well as succinctly elucidates the latest applications in THz functional device fabrication,including wireless communication devices,macromolecule detection sensors,environment monitoring sensors,and biomedical therapeutic devices.We further highlight recent applications of sustainable materials-based THz functional devices in hazardous substance detection,protein-based macromolecule detection,and environmental monitoring.Besides,this review explores the developmental prospects of integrating sustainable materials with THz functional devices,presenting their potential applications in the future.展开更多
Terahertz(THz)metamaterials,with their exceptional ability to precisely manipulate the phase,amplitude,polarization and orbital angular momentum(OAM)of electromagnetic waves,have demonstrated significant application p...Terahertz(THz)metamaterials,with their exceptional ability to precisely manipulate the phase,amplitude,polarization and orbital angular momentum(OAM)of electromagnetic waves,have demonstrated significant application potential across a wide range of fields.However,traditional design methodologies often rely on extensive parameter sweeps,making it challenging to address the increasingly complex and diverse application requirements.Recently,the integration of artificial intelligence(AI)techniques,particularly deep learning and optimization algorithms,has introduced new approaches for the design of THz metamaterials.This paper reviews the fundamental principles of THz metamaterials and their intelligent design methodologies,with a particular focus on the advancements in AI-driven inverse design of THz metamaterials.The AI-driven inverse design process allows for the creation of THz metamaterials with desired properties by working backward from the unit structures and array configurations of THz metamaterials,thereby accelerating the design process and reducing both computational resources and time.It examines the critical role of AI in improving both the functionality and design efficiency of THz metamaterials.Finally,we outline future research directions and technological challenges,with the goal of providing valuable insights and guidance for ongoing and future investigations.展开更多
A broadband polarization-independent terahertz multifunctional coding metasurface based on topological optimization using liquid crystal(LC)is proposed.The metasurface can achieve reconfigurability for beam steering a...A broadband polarization-independent terahertz multifunctional coding metasurface based on topological optimization using liquid crystal(LC)is proposed.The metasurface can achieve reconfigurability for beam steering and vortex beam generation within a frequency range of 0.68 THz–0.72 THz.Firstly,the metasurface unit is topologically optimized using the non-dominant sequencing genetic algorithms(NSGA-II)multi-objective optimization algorithm.By applying the LC’s electrically tunable refractive index properties,the metasurface unit enables polarization-independent 2-bit coding within a frequency range of 0.68 THz–0.72 THz.Then,based on the designed metasurface unit,the array arrangement of the metasurface is reverse-designed to achieve beam steering and vortex beam generation.The results show that,for beam steering,not only can polarization-independent steering of both single-and multi-beam be achieved within the 35°elevation angle range,but also independent control of the target angle of each beam in the multi-beam steering.For vortex beam generation,the metasurfaces can achieve the generation of single-and multi-vortex beams with topological charges l=±1,±2 within the 35elevation angle range,and the generation angles of each vortex beam in the multi-vortex beam can be independently controlled.This provides flexibility and diversity in the generation of vortex beams.Therefore,the proposed terahertz LC metasurface can realize flexible control of reconfigurable functions and has certain application prospects in terahertz communication,phased array radar,and vortex radar.展开更多
Terahertz(THz)radiation is rapidly emerging as a powerful tool with diverse applications,including high-speed imaging,laser-driven particle acceleration,and ultra-high frequency(UHF)communications.However,generating m...Terahertz(THz)radiation is rapidly emerging as a powerful tool with diverse applications,including high-speed imaging,laser-driven particle acceleration,and ultra-high frequency(UHF)communications.However,generating multipulse THz radiation with controllable time intervals remains a significant challenge.This study presents an approach to overcome this hurdle by exploiting the interaction between an electron beam and plasma.Using numerical simulations and theoretical analysis,we investigated the behavior of an electron beam within a plasma and its interaction with the longitudinal sheath field.This interaction resulted in the generation of multiple distinct THz pulses.We demonstrated that the plasma length adjustment allows for precise tuning of the interval between THz pulses.Moreover,the radiation intensity could be controlled by the electron beam energy and the electron bunch duration.The proposed scheme can generate multipulse THz radiation in a flexible and precise manner,paving the way for advancements in applications requiring high temporal resolution.展开更多
There is a growing interest in the rapid assessment of terahertz(THz)spectroscopy owing to its promising application pros-pects in nondestructive testing,security screening,and communication.In this study,we introduce...There is a growing interest in the rapid assessment of terahertz(THz)spectroscopy owing to its promising application pros-pects in nondestructive testing,security screening,and communication.In this study,we introduce a swift characterization method for THz spectroscopy that utilizes a THz-to-optical conversion system in a warm atomic vapor cell.By subtracting the photoluminescence(PL)spectra of cesium atoms with the THz field from those without the THz field,we obtained differential PL spectra that effectively characterized the 0.548 THz field.The differential PL spectra of Rydberg atoms offer the opportunity to quantify the THz field’s intensity and frequency,potentially paving the way for the development of THz spectroscopy based on warm atomic vapor cells.展开更多
The resonance generated by different mechanisms naturally has different characteristics in sensing,and these differences increase the potential for specific detection.We designed a metasurface with both a quasi-bound ...The resonance generated by different mechanisms naturally has different characteristics in sensing,and these differences increase the potential for specific detection.We designed a metasurface with both a quasi-bound state in continuum(QBIC)resonance and dipole resonance by conducting physical analyses such as electric field,current distribution,and multiple expansions on a dual-split-ring resonance with dipole resonance and a variant structure with symmetry breaking.On the other hand,the edge length of the slit was extended through a tilted split design,which further enhanced the QBIC resonance signal of the metasurface.In the sensing experiment of hyaluronic acid(HA),the limit of detection(LOD)obtained through frequency shift was 0.958 pmol∕μL,whereas the LOD obtained through the change in transmittance was 0.02 pmol∕μL.Our research findings contribute to the design of multiple resonant metasurfaces with different resonance modes,promoting further development in metasurface research and biosensing.展开更多
基金supported by grants from the National Key R&D Program of China,No.2017YFC0909200(to DC)the National Natural Science Foundation of China,No.62075225(to HZ)+1 种基金Zhejiang Provincial Medical Health Science and Technology Project,No.2023XY053(to ZP)Zhejiang Provincial Traditional Chinese Medical Science and Technology Project,No.2023ZL703(to ZP).
文摘Terahertz biotechnology has been increasingly applied in various biomedical fields and has especially shown great potential for application in brain sciences.In this article,we review the development of terahertz biotechnology and its applications in the field of neuropsychiatry.Available evidence indicates promising prospects for the use of terahertz spectroscopy and terahertz imaging techniques in the diagnosis of amyloid disease,cerebrovascular disease,glioma,psychiatric disease,traumatic brain injury,and myelin deficit.In vitro and animal experiments have also demonstrated the potential therapeutic value of terahertz technology in some neuropsychiatric diseases.Although the precise underlying mechanism of the interactions between terahertz electromagnetic waves and the biosystem is not yet fully understood,the research progress in this field shows great potential for biomedical noninvasive diagnostic and therapeutic applications.However,the biosafety of terahertz radiation requires further exploration regarding its two-sided efficacy in practical applications.This review demonstrates that terahertz biotechnology has the potential to be a promising method in the field of neuropsychiatry based on its unique advantages.
基金supported by the National Natural Science Foundation of China(No.12204251)。
文摘Strong-field terahertz waves not only have high peak power but also possess strong electromagnetic field components.When electrons encounters strong-field terahertz waves,a series of novel changes are induced,which have attracted extensive attention.This review first introduces common optical sources for strong-field terahertz emission,such as photoconductive antennas,optical rectification crystals,and air plasmas.Subsequently,recent applications of strong-field terahertz technology in material state modulation are presented,mainly including strong-field terahertz wave-driven hot carrier motion,coherent phonon control,spintronics,electron acceleration,and biomedicine.
基金supported by the National Natural Science Foundation of China(No.62375031)the Basic Research Project of Chongqing Science and Technology Commission(No.CSTC-2021jcyj-bsh0194)the Science and Technology Research Program of Chongqing Municipal Education Commission(No.KJQN202200602)。
文摘In this paper,a terahertz slotted waveguide array antenna is designed based on photonic crystal,which can realize efficient radiation of terahertz waves.The electromagnetic wave is fed from the rectangular waveguide at the bottom of the antenna,coupled to photonic crystal waveguide through photonic crystal cavity,and radiated outward through slots at the top layer of antenna.The simulation results show that the antenna achieves a peak gain of 13.45 dBi at 360 GHz,a half-power beam width of 10.9°,and a side lobe level of−13.9 dB.The antenna based on photonic crystal has the advantages of low profile,low loss,and high radiation efficiency,which can be applied to terahertz wireless communication systems.
基金supported by the Scientific Research Innovation Capability Support Project for Young Faculty (Grant No.ZYGXQNJSKYCXNLZCXMI3)the National Key Research and Development Program of China (Grant No.2022YFA1604402)+1 种基金the National Natural Science Foundation of China (Grant Nos.U23A6002,92250307,and 52225106)the Beijing Municipal Science and Technology Commission,Administrative Commission of Zhongguancun Science Park (Grant No.Z25110000692500)。
文摘Strong-field terahertz(THz) radiation holds significant potential in non-equilibrium state manipulation, electron acceleration, and biomedical effects. However, distortion-free detection of strong-field THz waveforms remains an essential challenge in THz science and technology. To address this issue, we propose a ferromagnetic detection scheme based on Zeeman torque sampling, achieving distortion-free strong-field THz waveform detection in Py films. Thickness-dependent characterization(3–21 nm) identifies peak detection performance at 21 nm within the investigated range. Furthermore, by structurally engineering the Py ferromagnetic layer, we demonstrate strong-field THz detection in symmetric Ta(3 nm)/Py(9 nm)/Ta(3 nm) heterostructure while simultaneously resolving Zeeman torque responses and collective spin-wave dynamics in asymmetric W(4 nm)/Py(9 nm)/Pt(2 nm)heterostructure. We calculated spin wave excitations and spin orbit torque distributions in asymmetric heterostructures, along with spin wave excitations in symmetric modes. This approach overcomes the sensitivity limitations of conventional techniques in strong-field conditions.
基金supported by the National Natural Science Foundation of China(Grant Nos.62005058 and 62365006)the Natural Science Foundation of Guangxi,China(Grant No.2020GXNSFBA238012)+2 种基金the China Postdoctoral Science Foundation(Grant No.2020M683726)the Innovation Project of Guangxi Graduate Education(Grant Nos.YCSW2024345 and YCBZ2025157)the Guangxi Key Laboratory of Automatic Detecting Technology and Instruments(Grant No.YQ24101).
文摘High-performance terahertz(THz)logic gate devices are crucial components for signal processing and modulation,playing a significant role in the application of THz communication and imaging.Here,we propose a THz broadband NOR logic encoder based on a graphene-metal hybrid metasurface.The unit structure consists of two symmetrical dual-gap metal split-ring resonators(DSRRs)arranged in a staggered configuration,with graphene strips embedded in their gaps.The NOR logic gate metadevice is controlled by the bias voltages independently applied to the two electrodes.Experiments show that when the bias voltages are applied to both electrodes,the metadevice achieves the NOR logic gate within a 0.52 THz bandwidth,with an average modulation depth above 80%.The experimental results match well with theoretical simulations.Additionally,the strong near-field coupling induced by the staggered DSRRs causes redshift at both LC resonance and dipole resonance.This phenomenon was demonstrated by coupled mode theory.Besides,we analyze the surface current distribution at resonances and propose four equivalent circuit models to elucidate the physical mechanisms of modulation under distinct loaded voltage conditions.The results not only advance modulation and logic gate designs for THz communication but also demonstrate significant potential applications in 6G networks,THz imaging,and radar systems.
基金Project supported by the National Key Research and Development Program of China(Grant No.2023YFF0719200)the National Natural Science Foundation of China(Grant Nos.62322115,U24A20226,61988102,and 62435010)+1 种基金the 111 Project(Grant No.D18014)the Science and Technology Commission of Shanghai Municipality(Grant Nos.22JC1400200 and 21S31907400)。
文摘The research on two-dimensional(2D)magnetic materials and their heterostructures is crucial in fields like spintronics,materials science,and condensed matter physics.This study uses terahertz(THz)time-domain spectroscopy to investigate ultrafast electron transport properties in both van der Waals Fe_(4)GeTe_(2)films and Bi_(2)Te_(3)/Fe_(4)GeTe_(2)ferromagnetic/topological heterostructures.Our results show that these heterostructures exhibit effective THz electromagnetic shielding.The complex conductivity spectra of Fe_(4)GeTe_(2)films and Bi_(2)Te_(3)/Fe_(4)GeTe_(2)heterostructures with varying Fe_(4)GeTe_(2)thicknesses are analyzed using the Drude-Smith model.We quantitatively examine how Fe_(4)GeTe_(2)layer thickness affects the direct current conductivity,plasma frequency,carrier momentum scattering time,and back-scattering coefficient.As the number of Fe_(4)GeTe_(2)layers increases,intra-layer back-scattering events for charge carriers become more frequent.This work provides THz frequency spectra for both Fe_(4)GeTe_(2)and Bi_(2)Te_(3)/Fe_(4)GeTe_(2),aiding in the design and optimization of THz modulators and detectors.
基金supported by the National Key Research and Development Program of China(2020YFB1805700,2018YFB1801500&2018YFB2201700)the Natural National Science Foundation of China under Grant 61771424the Natural Science Foundation of Zhejiang Province under Grant LZ18F010001 and Zhejiang Lab(no.2020LC0AD01).
文摘With the explosion of wireless data rates,the terahertz(THz)band(0.1–10 THz)is envisioned as a promising candidate to break the existing bandwidth bottleneck and satisfy the ever-increasing capacity demand.The THz wireless communications feature a number of attractive properties,such as potential terabit-per-second capacity and high energy efficiency.In this paper,an overview on the state-of-the-art THz communications is studied,with a special focus on key technologies of THz transceivers and THz communication systems.The recent progress on both electronic and photonic THz transmitters are presented,and then the THz receivers operating in direct-and heterodyne reception modes are individually surveyed.Based on the THz transceiver schemes,three kinds of THz wireless communication systems are reviewed,including solid-state electronic systems,photonics-assisted systems and all-photonics systems.The prospective key enabling technologies,corresponding challenges and research directions for lighting up high-speed THz communication systems are discussed as well.
基金Supported by the National Natural Science Foundation of China(61988102,62401113,92463308)the National Safety Academic Fund(U2130113)+2 种基金the Sichuan Science and Technology Program(2022JDJQ0065)the Chengdu Science and Technology Program(2024-YF05-01803-SN)the Sichuan Provincial Administration of Traditional Chinese Medicine(2024MS512)and the from Key Laboratory of THz Technology,Ministry of Education.
文摘Fibroblasts support a broad range of essential organ functions via microarchitectural,biomechanical,and biochemical cues.Despite great advances in fluorescence,photoacoustic conversion,and Raman scattering over the past decades,their invasiveness and limited spatial resolution hinder the characterization of fibroblasts in a single cell.Here,taking mouse embryonic fibroblasts(MEFs)as an example,we propose a novel noninvasive approach to investigate the compositional distribution of MEFs at the single-cell scale via terahertz(THz)nanos⁃copy.Compared to the topological morphology,THz nano-imaging enables the component-based visualization of MEFs,such as the membrane,cytoplasm,nucleus,and extracellular vesicles(EVs).Notably,we demonstrate the real-space observation of the influence of rapamycin treatment on the increase of EVs in MEFs.Moreover,the line-cut and area-statistical analysis establishes the relationship between the topological morphology and the THz near-field amplitudes for different cellular components of MEFs.This work provides a new pathway to char⁃acterize the effects of pharmaceutical treatments,with potential applications in disease diagnosis and drug devel⁃opment.
基金Supported by the National Natural Science Foundation of China(61988102,62401113,92463308)。
文摘Enamel demineralization often occurs in the early stage of dental caries.Studying the microscopic mechanism of enamel demineralization is essential to prevent and treat dental caries.Terahertz(THz)technolo⁃gy,especially continuous wave(CW)THz near-field scanning microscopy(THz-SNOM)with its nanoscale reso⁃lution,can be promising in biomedical imaging.In addition,compared with traditional THz time-domain spec⁃troscopy(TDS),portable solid-state source as the emission has higher power and SNR,lower cost,and can ob⁃tain more precise imaging.In this study,we employ CW THz-SNOM to further break the resolution limitations of conventional THz imaging techniques and successfully achieve the near-field imaging of demineralized enamel at the nanoscale.We keenly observe that the near-field signal of the enamel significantly lowers as demineralization deepens,mainly due to the decrease in permittivity.This new approach offers valuable insights into the micro⁃scopic processes of enamel demineralization,laying the foundation for further research and treatment.
文摘Compared to traditional single-frequency bound states in the continuum(BIC),dual-band BIC of-fers higher degrees of freedom and functionality.Moveover,implementing independent control of dual-band BICs can further enhance their advantages and maximize their performance.This study presents a design for a dielectric metasurface that achieves dual-band BICs in the terahertz(THz)range.By adjusting two asym-metry parameters of the structure,independent control of the two symmetry-protected BICs is achieved.Fur-thermore,by varying the shape of the silicon holes,the design's robustness to geometric variations is demon-strated.Finally,the test results show that the figures of merit(FOMs)for both BICs reach 109.This work provides a new approach for realizing and tuning dual-frequency BICs,offering expanded possibilities for applications in multimode lasers,nonlinear optics,multi-channel filtering,and optical sensing.
基金Supported by the National Key R&D Program of China(2023YFD2101001)National Natural Science Foundation of China(32202144,61807001)。
文摘To address the issues of peak overlap caused by complex matrices in agricultural product terahertz(THz)spectral signals and the dynamic,nonlinear interference induced by environmental and system noise,this study explores the feasibility of adaptive-signal-decomposition-based denoising methods to improve THz spectral quality.THz time-domain spectroscopy(THz-TDS)combined with an attenuated total reflection(ATR)accessory was used to collect THz absorbance spectra from 48 peanut samples.Taking the quantitative prediction model of peanut moisture content based on THz-ATR as an example,wavelet transform(WT),empirical mode decomposition(EMD),local mean decomposition(LMD),and its improved methods-segmented local mean decomposition(SLMD)and piecewise mirror extension local mean decomposition(PME-LMD)-were employed for spectral denoising.The applicability of different denoising methods was evaluated using a support vector regression(SVR)model.Experimental results show that the peanut moisture content prediction model constructed after PME-LMD denoising achieved the best performance,with a root mean square error(RMSE),coefficient of determination(R^(2)),and mean absolute percentage error(MAPE)of 0.010,0.912,and 0.040,respectively.Compared with traditional methods,PME-LMD significantly improved spectral quality and model prediction performance.The PME-LMD denoising strategy proposed in this study effectively suppresses non-uniform noise interference in THz spectral signals,providing an efficient and accurate preprocessing method for THz spectral analysis of agricultural products.This research provides theoretical support and technical guidance for the application of THz technology for detecting agricultural product quality.
基金supported by the National Natural Science Foundation of China under Grant No. 50971094, 61171051Beijing Key Project of Science and Technology Development under Grant No. KZ201310028032
文摘The terahertz time-domain spectroscopy （THz-TDS） system and the related technology and the applications in Capital Normal University are presented. The most often used THz-TDS system as a spectroscopic measurement setup in our lab is introduced in detail, including the THz radiation source, the THz detection method and its measurement, and the control system. THz spectra of various materials is summarized and discussed. These materials include but not limited to two kinds of typical matter-the illegal drugs and explosives. The biological macro-molecules, cosmetics and fine chemical materials, edible pigments and food additives, homocysteic acid and related compounds, heavy ions in soil, Chinese medicines, tobacco and crops, oil and chemical products, carbon nanotubes, superconductors, and various semiconductors and their heterojunctions, are presented. THz emissions from the InAs and InN semiconductors surface are compared. THz spectral investigation of metallic mesh structures is summarized. Finally, an outlook of THz spectroscopic applications is given.
文摘Resonant linear and nonlinear properties in terahertz range of 2D materials graphene and silicene placed into a bias magnetic field are investigated theoretically on the base of the quasi-classical kinetic theory. When the electromagnetic frequency is close to the cyclotron one, the linear conductivity increases two orders. Under the resonant frequencies nonlinearity becomes essential at low magnitudes of terahertz electric fields. In absence of a bias magnetic field the nonlinear dependences of the surface electric currents on terahertz electric field are practically the same simulated from kinetics and electron hydrodynamics with nonzero “kinetic” electron effective mass. Graphene possesses higher values of nonlinearity of the resonant conductivity, whereas in absence of a bias magnetic field, the electron nonlinearity is higher in silicene.
基金supported by the National Natural Science Foun-dation of China(Grant Nos.62371258,62335012,62205160,and 62435010)the Tianjin Youth Science and Technology Talent Project(Grant No.QN20230227)+1 种基金the Natural Science Foundation of Tianjin(Grant No.24JCYBJC01860)the Fundamental Research Funds for the Central Universities,Nan-kai University(Grant No.075-63253215).
文摘With the urgently increasing demand for high-speed and large-capacity communication trans-mission,there remains a critical need for tunable terahertz(THz)devices with multi-channel in 5G/6G communication systems.A magnetic phase-coding meta-atom(MPM)is formed by the heterogeneous integration of La:YIG magneto-optical(MO)materials and Si microstructures.The MPM couples the magnetic induction phase of spin states with the propagation phase and can simultaneously satisfy the required output phase for dual frequencies under various external magnetic fields to realize the dynamic beam steering among multiple channels at 0.25 and 0.5 THz.The energy ratio of the target direction can reach 96.5%,and the nonreciprocal one-way transmission with a max isolation of 29.8 dB is realized due to the nonreciprocal phase shift of the MO layer.This nonreciprocal mechanism of magnetic induction reshaping of wavefront significantly holds promise for advancing integrated multi-functional THz devices with the characteristics of low-crosstalk,multi-channel,and multi-frequency,and has great potential to promote the development of THz large-capacity and high-speed communication.
基金the financial support provided by Zhejiang Provincial Natural Science Foundation of China under Grant No.LZ23C130006.
文摘Terahertz(THz)devices,owing to their distinctive optical properties,have achieved myriad applications in diverse domains including wireless communication,medical imaging therapy,hazardous substance detection,and environmental governance.Concurrently,to mitigate the environmental impact of electronic waste generated by traditional materials,sustainable materialsbased THz functional devices are being explored for further research by taking advantages of their eco-friendliness,cost-effective,enhanced safety,robust biodegradability and biocompatibility.This review focuses on the origins and distinctive biological structures of sustainable materials as well as succinctly elucidates the latest applications in THz functional device fabrication,including wireless communication devices,macromolecule detection sensors,environment monitoring sensors,and biomedical therapeutic devices.We further highlight recent applications of sustainable materials-based THz functional devices in hazardous substance detection,protein-based macromolecule detection,and environmental monitoring.Besides,this review explores the developmental prospects of integrating sustainable materials with THz functional devices,presenting their potential applications in the future.
基金supported by the National Key R and D Program of China(No.2022YFF0604801)the National Natural Science Foundation of China(Nos.62271056,62171186,62201037)+3 种基金the Technology Innovation Center of Infrared Remote Sensing Metrology Technology of State Administration for Market Regulation(No.AKYKF2423)the Beijing Natural Science Foundation of China-Haidian Original Innovation Joint Fund(No.L222042)the Open Research Fund of State Key Laboratory of Millimeter Waves(No.K202326)the 111 Project of China(No.B14010).
文摘Terahertz(THz)metamaterials,with their exceptional ability to precisely manipulate the phase,amplitude,polarization and orbital angular momentum(OAM)of electromagnetic waves,have demonstrated significant application potential across a wide range of fields.However,traditional design methodologies often rely on extensive parameter sweeps,making it challenging to address the increasingly complex and diverse application requirements.Recently,the integration of artificial intelligence(AI)techniques,particularly deep learning and optimization algorithms,has introduced new approaches for the design of THz metamaterials.This paper reviews the fundamental principles of THz metamaterials and their intelligent design methodologies,with a particular focus on the advancements in AI-driven inverse design of THz metamaterials.The AI-driven inverse design process allows for the creation of THz metamaterials with desired properties by working backward from the unit structures and array configurations of THz metamaterials,thereby accelerating the design process and reducing both computational resources and time.It examines the critical role of AI in improving both the functionality and design efficiency of THz metamaterials.Finally,we outline future research directions and technological challenges,with the goal of providing valuable insights and guidance for ongoing and future investigations.
基金Project supported by the Open Fund of Wuhan National Research Center for Optoelectronics(Grant No.2022WNLOKF012)the National College Students Innovation Innovation and Entrepreneurship Training Program(Grant No.2023102930147).
文摘A broadband polarization-independent terahertz multifunctional coding metasurface based on topological optimization using liquid crystal(LC)is proposed.The metasurface can achieve reconfigurability for beam steering and vortex beam generation within a frequency range of 0.68 THz–0.72 THz.Firstly,the metasurface unit is topologically optimized using the non-dominant sequencing genetic algorithms(NSGA-II)multi-objective optimization algorithm.By applying the LC’s electrically tunable refractive index properties,the metasurface unit enables polarization-independent 2-bit coding within a frequency range of 0.68 THz–0.72 THz.Then,based on the designed metasurface unit,the array arrangement of the metasurface is reverse-designed to achieve beam steering and vortex beam generation.The results show that,for beam steering,not only can polarization-independent steering of both single-and multi-beam be achieved within the 35°elevation angle range,but also independent control of the target angle of each beam in the multi-beam steering.For vortex beam generation,the metasurfaces can achieve the generation of single-and multi-vortex beams with topological charges l=±1,±2 within the 35elevation angle range,and the generation angles of each vortex beam in the multi-vortex beam can be independently controlled.This provides flexibility and diversity in the generation of vortex beams.Therefore,the proposed terahertz LC metasurface can realize flexible control of reconfigurable functions and has certain application prospects in terahertz communication,phased array radar,and vortex radar.
基金supported by the National Natural Science Foundation of China(Grant No.12175058)the National Science Fund of Hunan Province for Distinguished Young Scholars(Grant No.2024JJ2009)。
文摘Terahertz(THz)radiation is rapidly emerging as a powerful tool with diverse applications,including high-speed imaging,laser-driven particle acceleration,and ultra-high frequency(UHF)communications.However,generating multipulse THz radiation with controllable time intervals remains a significant challenge.This study presents an approach to overcome this hurdle by exploiting the interaction between an electron beam and plasma.Using numerical simulations and theoretical analysis,we investigated the behavior of an electron beam within a plasma and its interaction with the longitudinal sheath field.This interaction resulted in the generation of multiple distinct THz pulses.We demonstrated that the plasma length adjustment allows for precise tuning of the interval between THz pulses.Moreover,the radiation intensity could be controlled by the electron beam energy and the electron bunch duration.The proposed scheme can generate multipulse THz radiation in a flexible and precise manner,paving the way for advancements in applications requiring high temporal resolution.
基金the CAS Project for Young Scientists in Basic Research(No.YSBR-042)the National Natural Science Foundation of China(Nos.12125508,11935020)+2 种基金Program of Shanghai Academic/Technology Research Leader(No.21XD1404100)the Shanghai Pilot Program for Basic Research-Chinese Academy of SciencesShanghai Branch(No.JCYJ-SHFY-2021-010).
文摘There is a growing interest in the rapid assessment of terahertz(THz)spectroscopy owing to its promising application pros-pects in nondestructive testing,security screening,and communication.In this study,we introduce a swift characterization method for THz spectroscopy that utilizes a THz-to-optical conversion system in a warm atomic vapor cell.By subtracting the photoluminescence(PL)spectra of cesium atoms with the THz field from those without the THz field,we obtained differential PL spectra that effectively characterized the 0.548 THz field.The differential PL spectra of Rydberg atoms offer the opportunity to quantify the THz field’s intensity and frequency,potentially paving the way for the development of THz spectroscopy based on warm atomic vapor cells.
文摘The resonance generated by different mechanisms naturally has different characteristics in sensing,and these differences increase the potential for specific detection.We designed a metasurface with both a quasi-bound state in continuum(QBIC)resonance and dipole resonance by conducting physical analyses such as electric field,current distribution,and multiple expansions on a dual-split-ring resonance with dipole resonance and a variant structure with symmetry breaking.On the other hand,the edge length of the slit was extended through a tilted split design,which further enhanced the QBIC resonance signal of the metasurface.In the sensing experiment of hyaluronic acid(HA),the limit of detection(LOD)obtained through frequency shift was 0.958 pmol∕μL,whereas the LOD obtained through the change in transmittance was 0.02 pmol∕μL.Our research findings contribute to the design of multiple resonant metasurfaces with different resonance modes,promoting further development in metasurface research and biosensing.
