With the rapid development of detection technology and artificial intelligence,the widespread use of multispectral detectors has increased challenges to stealth capabilities.This paper presents a bispectral camouflage...With the rapid development of detection technology and artificial intelligence,the widespread use of multispectral detectors has increased challenges to stealth capabilities.This paper presents a bispectral camouflage metasurface with microwave diffuse emission and tunable infrared(IR)emissivity,achieving an integrated design for radar cross-section(RCS)reduction and tunable IR emissivity.The structure consists of layers from bottom to top:aerogel felt,indium-tin-oxide(ITO),air,polyethylene terephthalate(PET),and ITO.It reduces RCS through microwave diffuse reflection and adjusts IR emissivity by controlling the ITO fill ratio.Both simulations and experiments demonstrate effective suppression of electromagnetic(EM)wave backscattering within4.5-10.3 GHz,achieving radar invisibility.The tunable IR emissivity ranges from 0.2 to 0.7 with good thermal insulation.This design alleviates issues related to structural thickness and processing complexity and avoids increased thermal load from microwave absorption,offering better tunable IR emissivity for various thermal camouflage environments.This metasurface holds significant promise for multispectral stealth and IR camouflage applications.展开更多
A reconfigurable metasurface based on optical control provides a control paradigm for integrating multiple functions at the same aperture,which effectively expands the freedom of control.However,the traditional light ...A reconfigurable metasurface based on optical control provides a control paradigm for integrating multiple functions at the same aperture,which effectively expands the freedom of control.However,the traditional light control method requires the light source to directly illuminate the photosensitive device,which forces the metasurface to be placed only according to the light emitter position,and even to need to be integrated on the light emitter,limiting the application scenarios of light-controlled reconfigurable metasurfaces.In this work,a light control method based on optical fiber is proposed,which guides and controls the light propagation path through optical fiber.The metasurface can be flexibly deployed,breaking through the limitation of physical space.As a verification,photoresistors are embedded in the metasurface,and the active device is directly excited by the light source as a driving signal to realize the switching of a polarization conversion function.The experimental results show that the optical-fiber-controlled metasurface can achieve linear-to-linear polarization conversion in the light environment and linear-to-circular polarization conversion in the dark environment.This work paves a new way,to our knowledge,to achieve a light-controlled metasurface,which enriches the family of intelligent metasurfaces and has great potential in many fields.展开更多
To adapt to the complex environment where low infrared emissivity and high infrared emissivity coexist,a radar stealth-infrared camouflage compatibility metasurface requires meta-atoms with customized infrared emissiv...To adapt to the complex environment where low infrared emissivity and high infrared emissivity coexist,a radar stealth-infrared camouflage compatibility metasurface requires meta-atoms with customized infrared emissivity.Generally,the infrared emissivity is determined by the occupation ratio.However,the high occupation ratio will interfere with the scattering reduction function due to the Lorentz resonance from the metal patch.To address the problem,a method for decoupling Lorentz resonance is proposed in this paper.By shifting the resonant frequency of the metal patch to a high frequency,the Lorentz resonance is suppressed in the frequency band of scattering reduction.To verify the method,a single functional layer metasurface with microwave scattering reduction and customized infrared emissivity is designed.The scattering reduction at 3.5–5.5 GHz is realized through the polarization conversion.Meanwhile,the infrared emissivity of the metasurface can be gradient-designed by changing the occupation ratios of the meta-atoms.Compared with the initial design,the improved metasurface expands the infrared emissivity range from 0.60–0.80 to 0.51–0.80,and the scattering reduction effect remains unchanged.The experimental results agree with the simulated results.The work enriches the infrared emissivity function,which can be applied to camouflage in complex spectrum backgrounds.展开更多
Programmable digital coding metasurfaces(PDCMs)can manipulate electromagnetic waves with high degrees of freedom,significantly enriching metasurface designs.However,most PDCMs are limited to the control of a single po...Programmable digital coding metasurfaces(PDCMs)can manipulate electromagnetic waves with high degrees of freedom,significantly enriching metasurface designs.However,most PDCMs are limited to the control of a single polarization,which cannot meet the requirements of the high integration of intelligent components.To further improve the practicability and flexibility of metasurfaces,we propose an integrated paradigm for spin-decoupling PDCMs based on light emitting diode arrays that fully embed the photoresistor as a part of the meta-atom to independently manipulate the wavefront in different polarizations.As a proof of concept,PDCMs were simulated,fabricated,and measured to verify the feasibility and effectiveness of the proposed method.The functions of scattering and vortices are verified at different polarizations,demonstrating that the metasurface can tailor the EM functions in six channels.This study can improve the integration of intelligent control metasurfaces and lay a solid foundation for their development.展开更多
Coding metasurfaces can manipulate electromagnetic wave in real time with high degree of freedom,the fascinating properties of which enrich the metasurface design with a wide range of application prospects.However,mos...Coding metasurfaces can manipulate electromagnetic wave in real time with high degree of freedom,the fascinating properties of which enrich the metasurface design with a wide range of application prospects.However,most of the coding metasurfaces are designed based on external excitation framework with the wired electrical or wireless light control devices,thus inevitably causing the interference with electromagnetic wave transmission and increasing the complexity of the metasurface design.In this work,a simplistic framework of single-pixel-programmable metasurfaces integrated with a capsuled LED array is proposed to dynamically control electromagnetic wave.The framework fully embeds the photoresistor in the meta-atom,controlling the LED array to directly illuminate the photoresistor to modulate the phase response.With this manner,the complex biasing network is transformed to the universal LED array,which means the physical control framework can be transformed to a software framework,and thus the functions of the metasurface can be freely manipulated by encoding the capsuled LED array avoiding mutual coupling of adjacent meta-atoms in real time.All the results verify that the far-field scattering pattern can be customized with this singlepixel-programmable metasurface.Encouragingly,this work provides a universal framework for coding metasurface design,which lays the foundation for metasurface intelligent perception and adaptive modulation.展开更多
For camouflage applications,the performance requirements for metamaterials in different electromagnetic spectra are usually contradictory,which makes it difficult to develop satisfactory design schemes with multispect...For camouflage applications,the performance requirements for metamaterials in different electromagnetic spectra are usually contradictory,which makes it difficult to develop satisfactory design schemes with multispectral compatibility.Fortunately,empowered by machine learning,metamaterial design is no longer limited to directly solving Maxwell’s equations.The design schemes and experiences of metamaterials can be analyzed,summarized,and learned by computers,which will significantly improve the design efficiency for the sake of practical engineer-ing applications.Here,we resort to the machine learning to solve the multispectral compatibility problem of metamaterials and demonstrate the design of a new metafilm with multiple mechanisms that can realize small microwave scattering,low infrared emissivity,and visible transparency simultaneously using a multilayer back-propagation neural network.The rapid evolution of structural design is realized by establishing a mapping between spectral curves and structural parameters.By training the network with different materials,the designed network is more adaptable.Through simulations and experimental verifications,the designed architecture has good accuracy and robustness.This paper provides a facile method for fast designs of multispectral metafilms that can find wide applications in satellite solar panels,aircraft windows,and others.展开更多
Metasurfaces have intrigued long-standing research interests and developed multitudinous compelling applications owing to their unprecedented capability for manipulating electromagnetic waves,and the emerging programm...Metasurfaces have intrigued long-standing research interests and developed multitudinous compelling applications owing to their unprecedented capability for manipulating electromagnetic waves,and the emerging programmable coding metasurfaces(PCMs)provide a real-time reconfigurable platform to dynamically implement customized functions.Nevertheless,most existing PCMs can only act on the single polarization state or perform in the limited polarization channel,which immensely restricts their practical application in multitask intelligent metadevices.Herein,an appealing strategy of the PCM is proposed to realize tunable functions in co-polarized reflection channels of orthogonal circularly polarized waves and in co-polarized and cross-polarized reflection channels of orthogonal linearly polarized waves from 9.0 to 10.5 GHz.In the above six channels,the spindecoupled programmable meta-atom can achieve high-efficiency reflection and 1-bit digital phase modulation by selecting the specific ON/OFF states of two diodes,and the phase coding sequence of the PCM is dynamically regulated by the field-programmable gate array to generate the desired function.A proof-of-concept prototype is constructed to verify the feasibility of our methodology,and numerous simulation and experimental results are in excellent agreement with the theoretical predictions.This inspiring design opens a new avenue for constructing intelligent metasurfaces with higher serviceability and flexibility,and has tremendous application potential in communication,sensing,and other multifunctional smart metadevices.展开更多
Metasurface has provided unprecedented freedoms in manipulating electromagnetic(EM) waves, exhibiting fascinating functions. Conventionally, these functions are implemented right on metasurfaces, where spatial modulat...Metasurface has provided unprecedented freedoms in manipulating electromagnetic(EM) waves, exhibiting fascinating functions. Conventionally, these functions are implemented right on metasurfaces, where spatial modulations on EM wave amplitudes or phases are achieved by meta-atoms. This study proposes the concept of virtual metasurface(VM), which is formed by arrays of foci away from the entity metasurface. Unlike conventional metasurfaces, spatial modulations on the amplitudes or phases of EM waves occur in the air, with a focal length distance from the entity metasurface. As a proof of concept, we demonstrated a transmissive VM. The entity metasurface consists of transmissive focusing metasurface tiles(TFMTs) with the same focal length. Two TFMTs were designed with phase difference π to enable the most typical checkerboard configuration. The TFMTs were assembled to form the entity metasurface, whereas their foci formed the VM. Due to the π phase difference among adjacent foci, EM propagation along the normal direction was cancelled, leading to four tilted far-field beams. The concept of VM can be readily extended to higher frequencies from terahertz to optical regimes and may find wide applications in communication, camouflage, and other fields.展开更多
The high degree of freedom of multimechanism metasurfaces has greatly facilitated multifunction or even multiphysics design for practical applications.In this work,to achieve camouflages simultaneously in microwave,in...The high degree of freedom of multimechanism metasurfaces has greatly facilitated multifunction or even multiphysics design for practical applications.In this work,to achieve camouflages simultaneously in microwave,infrared,and optical regimes,we propose a multimechanism-empowered metasurface composed of four elemental indium-tin-oxide-based meta-atoms.Each meta-atom can modulate microwaves both in phase and magnitude through polarization conversion and resonance absorption,which can realize radar stealth at 8–14 GHz.The reflective amplitude is less than−10 dB.When the incident angle increases to 60°,the reflective amplitude is still less than−3 dB.The far-field scattering patterns of microwaves are modulated by destructive interferences of reflected waves,which results in diffusion-like scattering due to randomly distributed reflection phases on the metasurface.The superposition of microwave absorption and diffuse reflection enables broadband microwave scattering reduction of the metasurface.Meanwhile,the emissivity of four types of meta-atoms covers from 0.3–0.8 at 3–14μm due to delicately designed occupation ratios.The infrared radiation of the metasurface exhibits the characteristics of digital camouflage in infrared imaging.To demonstrate this method,prototypes were fabricated and measured.The measured results are consistent with the simulated ones.The angular stability in the microwave range within 0°–60°was also demonstrated.This work presents an approach to achieving multispectrum functions with integrated multimechanisms in a single functional metasurface layer and offers a new methodology for custom-designing infrared performance.Moreover,the simplicity of the structure offers significant cost control and large-scale fabrication advantages.展开更多
基金Shaanxi Creative Talents Promotion PlanTechnological Innovation Team(2023-CX-TD-48)Natural Science Foundation of Shaanxi Province(2024JC-YBMS-462,2024JC-YBMS-504)National Natural Science Foundation of China(52272101,62201609,62101588)。
文摘With the rapid development of detection technology and artificial intelligence,the widespread use of multispectral detectors has increased challenges to stealth capabilities.This paper presents a bispectral camouflage metasurface with microwave diffuse emission and tunable infrared(IR)emissivity,achieving an integrated design for radar cross-section(RCS)reduction and tunable IR emissivity.The structure consists of layers from bottom to top:aerogel felt,indium-tin-oxide(ITO),air,polyethylene terephthalate(PET),and ITO.It reduces RCS through microwave diffuse reflection and adjusts IR emissivity by controlling the ITO fill ratio.Both simulations and experiments demonstrate effective suppression of electromagnetic(EM)wave backscattering within4.5-10.3 GHz,achieving radar invisibility.The tunable IR emissivity ranges from 0.2 to 0.7 with good thermal insulation.This design alleviates issues related to structural thickness and processing complexity and avoids increased thermal load from microwave absorption,offering better tunable IR emissivity for various thermal camouflage environments.This metasurface holds significant promise for multispectral stealth and IR camouflage applications.
基金National Key Research and Development Program of China(2022YFB3806200)National Natural Science Foundation of China(62201609,62401614,62401617)。
文摘A reconfigurable metasurface based on optical control provides a control paradigm for integrating multiple functions at the same aperture,which effectively expands the freedom of control.However,the traditional light control method requires the light source to directly illuminate the photosensitive device,which forces the metasurface to be placed only according to the light emitter position,and even to need to be integrated on the light emitter,limiting the application scenarios of light-controlled reconfigurable metasurfaces.In this work,a light control method based on optical fiber is proposed,which guides and controls the light propagation path through optical fiber.The metasurface can be flexibly deployed,breaking through the limitation of physical space.As a verification,photoresistors are embedded in the metasurface,and the active device is directly excited by the light source as a driving signal to realize the switching of a polarization conversion function.The experimental results show that the optical-fiber-controlled metasurface can achieve linear-to-linear polarization conversion in the light environment and linear-to-circular polarization conversion in the dark environment.This work paves a new way,to our knowledge,to achieve a light-controlled metasurface,which enriches the family of intelligent metasurfaces and has great potential in many fields.
基金National Key Research and Development Program of China(2022YFB3806200)Natural Science Foundation of Shaanxi Province(2024JC-YBMS-504,2024JC-YBQN-0617)+1 种基金China Postdoctoral Science Foundation(2023M744291)Key Scientific and Technological Innovation Team of Shaanxi Province(2023-CX-TD-48)。
文摘To adapt to the complex environment where low infrared emissivity and high infrared emissivity coexist,a radar stealth-infrared camouflage compatibility metasurface requires meta-atoms with customized infrared emissivity.Generally,the infrared emissivity is determined by the occupation ratio.However,the high occupation ratio will interfere with the scattering reduction function due to the Lorentz resonance from the metal patch.To address the problem,a method for decoupling Lorentz resonance is proposed in this paper.By shifting the resonant frequency of the metal patch to a high frequency,the Lorentz resonance is suppressed in the frequency band of scattering reduction.To verify the method,a single functional layer metasurface with microwave scattering reduction and customized infrared emissivity is designed.The scattering reduction at 3.5–5.5 GHz is realized through the polarization conversion.Meanwhile,the infrared emissivity of the metasurface can be gradient-designed by changing the occupation ratios of the meta-atoms.Compared with the initial design,the improved metasurface expands the infrared emissivity range from 0.60–0.80 to 0.51–0.80,and the scattering reduction effect remains unchanged.The experimental results agree with the simulated results.The work enriches the infrared emissivity function,which can be applied to camouflage in complex spectrum backgrounds.
基金supported in part by the National Key Research and Development Program of China under Grant 2022YFB3806200the National Natural Science Foundation of China under Grants 62101588 and 62201609.
文摘Programmable digital coding metasurfaces(PDCMs)can manipulate electromagnetic waves with high degrees of freedom,significantly enriching metasurface designs.However,most PDCMs are limited to the control of a single polarization,which cannot meet the requirements of the high integration of intelligent components.To further improve the practicability and flexibility of metasurfaces,we propose an integrated paradigm for spin-decoupling PDCMs based on light emitting diode arrays that fully embed the photoresistor as a part of the meta-atom to independently manipulate the wavefront in different polarizations.As a proof of concept,PDCMs were simulated,fabricated,and measured to verify the feasibility and effectiveness of the proposed method.The functions of scattering and vortices are verified at different polarizations,demonstrating that the metasurface can tailor the EM functions in six channels.This study can improve the integration of intelligent control metasurfaces and lay a solid foundation for their development.
基金National Key Research and Development Program of China(2022YFB3806200)National Natural Science Foundation of China(12004437,61971435,62101588,62201609,62001504)Natural Science Foundation of Shaanxi Province(2022JM-352,2022JQ-630)。
文摘Coding metasurfaces can manipulate electromagnetic wave in real time with high degree of freedom,the fascinating properties of which enrich the metasurface design with a wide range of application prospects.However,most of the coding metasurfaces are designed based on external excitation framework with the wired electrical or wireless light control devices,thus inevitably causing the interference with electromagnetic wave transmission and increasing the complexity of the metasurface design.In this work,a simplistic framework of single-pixel-programmable metasurfaces integrated with a capsuled LED array is proposed to dynamically control electromagnetic wave.The framework fully embeds the photoresistor in the meta-atom,controlling the LED array to directly illuminate the photoresistor to modulate the phase response.With this manner,the complex biasing network is transformed to the universal LED array,which means the physical control framework can be transformed to a software framework,and thus the functions of the metasurface can be freely manipulated by encoding the capsuled LED array avoiding mutual coupling of adjacent meta-atoms in real time.All the results verify that the far-field scattering pattern can be customized with this singlepixel-programmable metasurface.Encouragingly,this work provides a universal framework for coding metasurface design,which lays the foundation for metasurface intelligent perception and adaptive modulation.
基金Natural Science Basic Research Program of Shaanxi Province(2020JQ-471,2020JQ-472)National Key Research and Development Program of China(SQ2017YFA0700201)National Natural Science Foundation of China(12004437,51802349,61971435).
文摘For camouflage applications,the performance requirements for metamaterials in different electromagnetic spectra are usually contradictory,which makes it difficult to develop satisfactory design schemes with multispectral compatibility.Fortunately,empowered by machine learning,metamaterial design is no longer limited to directly solving Maxwell’s equations.The design schemes and experiences of metamaterials can be analyzed,summarized,and learned by computers,which will significantly improve the design efficiency for the sake of practical engineer-ing applications.Here,we resort to the machine learning to solve the multispectral compatibility problem of metamaterials and demonstrate the design of a new metafilm with multiple mechanisms that can realize small microwave scattering,low infrared emissivity,and visible transparency simultaneously using a multilayer back-propagation neural network.The rapid evolution of structural design is realized by establishing a mapping between spectral curves and structural parameters.By training the network with different materials,the designed network is more adaptable.Through simulations and experimental verifications,the designed architecture has good accuracy and robustness.This paper provides a facile method for fast designs of multispectral metafilms that can find wide applications in satellite solar panels,aircraft windows,and others.
基金Air Force Engineering University(KGD080921020)Natural Science Basic Research Program of Shaanxi Province(2021JQ-363)+1 种基金Fundamental Research Funds for the Central Universities(2242022k30004)National Natural Science Foundation of China(61901508,61971435,62101589,62201609)。
文摘Metasurfaces have intrigued long-standing research interests and developed multitudinous compelling applications owing to their unprecedented capability for manipulating electromagnetic waves,and the emerging programmable coding metasurfaces(PCMs)provide a real-time reconfigurable platform to dynamically implement customized functions.Nevertheless,most existing PCMs can only act on the single polarization state or perform in the limited polarization channel,which immensely restricts their practical application in multitask intelligent metadevices.Herein,an appealing strategy of the PCM is proposed to realize tunable functions in co-polarized reflection channels of orthogonal circularly polarized waves and in co-polarized and cross-polarized reflection channels of orthogonal linearly polarized waves from 9.0 to 10.5 GHz.In the above six channels,the spindecoupled programmable meta-atom can achieve high-efficiency reflection and 1-bit digital phase modulation by selecting the specific ON/OFF states of two diodes,and the phase coding sequence of the PCM is dynamically regulated by the field-programmable gate array to generate the desired function.A proof-of-concept prototype is constructed to verify the feasibility of our methodology,and numerous simulation and experimental results are in excellent agreement with the theoretical predictions.This inspiring design opens a new avenue for constructing intelligent metasurfaces with higher serviceability and flexibility,and has tremendous application potential in communication,sensing,and other multifunctional smart metadevices.
基金National Key Research and Development Program of China(SQ2017YFA0700201,2017YFA0700202)National Natural Science Foundation of China(61971435,61731010,11874142)
文摘Metasurface has provided unprecedented freedoms in manipulating electromagnetic(EM) waves, exhibiting fascinating functions. Conventionally, these functions are implemented right on metasurfaces, where spatial modulations on EM wave amplitudes or phases are achieved by meta-atoms. This study proposes the concept of virtual metasurface(VM), which is formed by arrays of foci away from the entity metasurface. Unlike conventional metasurfaces, spatial modulations on the amplitudes or phases of EM waves occur in the air, with a focal length distance from the entity metasurface. As a proof of concept, we demonstrated a transmissive VM. The entity metasurface consists of transmissive focusing metasurface tiles(TFMTs) with the same focal length. Two TFMTs were designed with phase difference π to enable the most typical checkerboard configuration. The TFMTs were assembled to form the entity metasurface, whereas their foci formed the VM. Due to the π phase difference among adjacent foci, EM propagation along the normal direction was cancelled, leading to four tilted far-field beams. The concept of VM can be readily extended to higher frequencies from terahertz to optical regimes and may find wide applications in communication, camouflage, and other fields.
基金National Key Research and Development Program of China(2022YFB3806200)National Natural Science Foundation of China(62201609,62401614)+1 种基金Natural Science Basic Research Program of Shaanxi Province(2024JC-YBMS-504)Shaanxi Key Science and Technology Innovation Team Project(2023-CX-TD-48)。
文摘The high degree of freedom of multimechanism metasurfaces has greatly facilitated multifunction or even multiphysics design for practical applications.In this work,to achieve camouflages simultaneously in microwave,infrared,and optical regimes,we propose a multimechanism-empowered metasurface composed of four elemental indium-tin-oxide-based meta-atoms.Each meta-atom can modulate microwaves both in phase and magnitude through polarization conversion and resonance absorption,which can realize radar stealth at 8–14 GHz.The reflective amplitude is less than−10 dB.When the incident angle increases to 60°,the reflective amplitude is still less than−3 dB.The far-field scattering patterns of microwaves are modulated by destructive interferences of reflected waves,which results in diffusion-like scattering due to randomly distributed reflection phases on the metasurface.The superposition of microwave absorption and diffuse reflection enables broadband microwave scattering reduction of the metasurface.Meanwhile,the emissivity of four types of meta-atoms covers from 0.3–0.8 at 3–14μm due to delicately designed occupation ratios.The infrared radiation of the metasurface exhibits the characteristics of digital camouflage in infrared imaging.To demonstrate this method,prototypes were fabricated and measured.The measured results are consistent with the simulated ones.The angular stability in the microwave range within 0°–60°was also demonstrated.This work presents an approach to achieving multispectrum functions with integrated multimechanisms in a single functional metasurface layer and offers a new methodology for custom-designing infrared performance.Moreover,the simplicity of the structure offers significant cost control and large-scale fabrication advantages.
