Metasurfaces offer exceptional capabilities for controlling electromagnetic waves,enabling the realization of unique electromagnetic properties.As communication technology continues to evolve,metasurfaces present prom...Metasurfaces offer exceptional capabilities for controlling electromagnetic waves,enabling the realization of unique electromagnetic properties.As communication technology continues to evolve,metasurfaces present promising applications in wireless communications.This paper reviews the latest advancements in metasurface research within the communication sector,explores metasurface-based wireless relay technologies,and summarizes various wireless communication methods employing different types of metasurfaces across diverse modulation schemes.This paper provides a detailed discussion on the design of wireless communication systems based on coding metasurfaces to simplify transmitter architecture,as well as the development of intelligent coding metasurfaces in the communication field.It also elaborates on the application of vector vortex light fields in metasurface communication.Finally,it offers a forward-looking perspective on wireless communication systems that incorporate coded metasurfaces.This review aims to furnish researchers with a thorough understanding of the current state and future directions of coded metasurface applications in communications.展开更多
The investigation of topological transitions has opened up unprecedented avenues for scientific exploration in photonic metamaterials.However,previous studies mainly focused on exploring different types of three-dimen...The investigation of topological transitions has opened up unprecedented avenues for scientific exploration in photonic metamaterials.However,previous studies mainly focused on exploring different types of three-dimensional(3D)equifrequency surfaces and their topological transition processes in magnetic topological systems.In this work,we study the multiple photonic topological transitions and dual-frequency photonic Weyl points in the topological chiral metamaterials.Through effective medium theory and topological band theory,we systematically characterize and draw comprehensive topological phase diagrams associated with diverse 3D equifrequency surface configurations in nonmagnetic photonic systems.We further demonstrate that the resonance frequencyω0 and dual-frequency Weyl points are the critical points of these topological transitions.Notably,when the vacuum state is in contact with the phases I or III chiral metamaterials,the high-local and frequency chirality-dependent topological Fermi arc surface states arise.We reveal that the parameterωcan be used as a degree of freedom to regulate the bandwidth of such topological surface states.Moreover,different types of multichannel and directional topological photonic routings are achieved using the chirality-dependent Fermi arc surface states.We theoretically show that the physical mechanism of achieving these multichannel topological photonic routings is caused by the different interface properties.We could offer promising perspectives on 3D topological semimetal systems and provide more adaptability for multichannel devices in the nonmagnetic continuous media.展开更多
The post-earthquake field investigations reveal that the MW7.9 Wenchuan earthquake of 12th May 2008 ruptured three NE-striking imbricate reverse faults and another NW-trending reverse fault, along the middle Longmensh...The post-earthquake field investigations reveal that the MW7.9 Wenchuan earthquake of 12th May 2008 ruptured three NE-striking imbricate reverse faults and another NW-trending reverse fault, along the middle Longmenshan fold-and-thrust belt at the eastern margin of the Tibetan plateau. The fault-scarp features can be categorized into eight groups: simple thrust scarp, hanging-wall collapse scarp, simple pressure ridge, dextral pressure ridge, fault-related fold scarp, back-thrust pressure ridge, local normal fault scarp and crocodile-mouth-like scarp. The local normal scarp is first discovered in the reverse-faulting earthquakes as ever reported in the world. Field observation indicates that the Wenchuan earthquake surface rupture is dominated by reverse faulting with a minus right-lateral component, but the relative ratio varies from site to site. Also, the surface ruptures can be divided, for the first order, into two segments, the Yingxiu and Beichuan segments, corresponding to MW7.8 and MW7.57 events, respectively. The two segments further can be divided, for the second order, into four sub-segments in total, which are equivalent to four sub-events of MW7.46, MW7.69, MW6.99 and MW7.52, respectively. The fault segmentation, for different orders, shows a cascade-rupturing pattern and can explain why the quake time of the Wenchuan earthquake was so long as up to 100 second. Aftershock focal mechanisms are also used to constrain the fault geometry for the sub-segments, indicating that the seismogenic faults are listric at depth and in general, the fault plane becomes steeper northward, which enables the fault to accommodate larger strike-slip motion. This earthquake also confirms that the crustal shortening across the Longmenshan fold-and-thrust belt should be responsible for the growth of high topographic relief along the eastern margin of the Tibetan Plateau.展开更多
Metalens is the next generation of optical metasurfaces for compact imaging,sensing,and display applications that allow the phase,polarization,frequency,amplitude,angular momentum,etc.of the incident light to be desig...Metalens is the next generation of optical metasurfaces for compact imaging,sensing,and display applications that allow the phase,polarization,frequency,amplitude,angular momentum,etc.of the incident light to be designed with high degrees of freedom to meet the application requirements,which has attracted broad interest in the field of planar optics.One significant challenge in implementing applications for metalens is the efficient fabrication of largescale nanostructures with high resolution,robustness and uniform patterning.In this review,we first introduced the manufacturing techniques compatible with metasurfaces fabrication in detail,including masked lithography,maskless lithography,and additive manufacturing,discussed the limitations and provided some insights.Next,we introduced the applications of metalens from the perspective of non-imaging and imaging optics fields.Metalens can enhance the illumination effect,shape beams,and improve the energy conversion efficiency in non-imaging optics.In imaging optics,the role of metalens in replacing traditional optical components in lithography,astronomical observation,microscopic and endoscopic systems is demonstrated.Finally,the challenges that the metalens facing on the road to commercial application are discussed,and the field’s future development is prospected.展开更多
A brief review of recent progress in researches, productions and applications of full distributed fiber Raman photon sensors at China Jiliang University （CJLU） is presented. In order to improve the measurement dista...A brief review of recent progress in researches, productions and applications of full distributed fiber Raman photon sensors at China Jiliang University （CJLU） is presented. In order to improve the measurement distance, the accuracy, the space resolution, the ability of multi-parameter measurements, and the intelligence of full distributed fiber sensor systems, a new generation fiber sensor technology based on the optical fiber nonlinear scattering fusion principle is proposed. A series of new generation full distributed fiber sensors are investigated and designed, which consist of new generation ultra-long distance full distributed fiber Raman and Rayleigh scattering photon sensors integrated with a fiber Raman amplifier, auto-correction full distributed fiber Raman photon temperature sensors based on Raman correlation dual sources, full distributed fiber Raman photon temperature sensors based on a pulse coding source, full distributed fiber Raman photon temperature sensors using a fiber Raman wavelength shifter, a new type of Brillouin optical time domain analyzers （BOTDAs） integrated with a fiber Raman amplifier for replacing a fiber Brillouin amplifier, full distributed fiber Raman and Brillouin photon sensors integrated with a fiber Raman amplifier, and full distributed fiber Brillouin photon sensors integrated with a fiber Brillouin frequency shifter. The Internet of things is believed as one of candidates of the next technological revolution, which has driven hundreds of millions of class markets. Sensor networks are important components of the Internet of things. The full distributed optical fiber sensor network （Rayleigh, Raman, and Brillouin scattering） is a 3S （smart materials, smart structure, and smart skill） system, which is easy to construct smart fiber sensor networks. The distributed optical fiber sensor can be embedded in the power grids, railways, bridges, tunnels, roads, constructions, water supply systems, dams, oil and gas pipelines and other facilities, and can be integrated with wireless networks.展开更多
To enhance transmission eficiency of Pancharatnam Berry(PB)phase metasurfaces,multilayer split-ring resonators were proposed to develop encoding sequences.As per the generalized Snell's law,the deflection angle of...To enhance transmission eficiency of Pancharatnam Berry(PB)phase metasurfaces,multilayer split-ring resonators were proposed to develop encoding sequences.As per the generalized Snell's law,the deflection angle of the PB phase encoding metasurfaces depends on the metasurface period's size.Therefore,it is impossible to design an infinitesimal metasurface unit;consequently,the continuous transmission scattering angle cannot be obtained.In digital signal processing,this study introduces the Fourier convolution principle on encoding metasurface sequences to freely control the trausmitted scattering angles.Both addition and subtraction operations between two diferent encoding sequences were then performed to achieve the continuous variation of the scattering angle.Furthermore,we established that the Fourier convolution principle can be applied to the checkerboard coded metasur-faces.展开更多
In view of the fact that most invisibility devices focus on linear polarization cloaking and that the characteristics of mid-infrared cloaking are rarely studied,we propose a cross-circularly polarized invisibility ca...In view of the fact that most invisibility devices focus on linear polarization cloaking and that the characteristics of mid-infrared cloaking are rarely studied,we propose a cross-circularly polarized invisibility carpet cloaking device in the mid-infrared band.Based on the Pancharatnam–Berry phase principle,the unit cells with the cross-circular polarization gradient phase were carefully designed and constructed into a metasurface.In order to achieve tunable cross-circular polarization carpet cloaks,a phase change material is introduced into the design of the unit structure.When the phase change material is in amorphous and crystalline states,the proposed metasurface unit cells can achieve highefficiency cross-polarization conversion,and reflection intensity can be tuned.According to the phase compensation principle of carpet cloaking,we construct a metasurface cloaking device with a phase gradient using the designed unit structure.From the near-and far-field distributions,the cross-circular polarization cloaking property is confirmed in the broadband wavelength range of 9.3–11.4μm.The proposed cloaking device can effectively resist detection of cross-circular polarization.展开更多
Programmable hyper-coded holography has the advantage of being programmable as well as being flexibly modifiable.Digitally coded metamaterials with excellent electromagnetic modulation capability and the ability to co...Programmable hyper-coded holography has the advantage of being programmable as well as being flexibly modifiable.Digitally coded metamaterials with excellent electromagnetic modulation capability and the ability to control the phase to modulate the spatial radiation field through external excitation in the form of switching can be used to realize low-cost digital arrays.We design a 1-bit encoded programmable metasurface,which is electrically connected to control the PIN diode in the switching state and to switch the condition of each metasurface cell between“0”and“1.”Using the designed programmable metasurface,we can randomly encode the cell structure to realize single-focus focusing,multi-focusing,and simple holographic letter imaging.Based on the nonlinear holographic model,we employ the Gerchberg-Saxton improvement algorithm to modulate the energy distribution at the focus by adjusting the phase distribution.Importantly,we introduce the Fourier convolution principle to regulate the holographic imaging focus flexibly.展开更多
Based on the principle of super-symmetric lens with quadratic phase gradient transformation, combined with the principle of digital coding of metasurface, we propose a wide-angle coded metalens for focusing control in...Based on the principle of super-symmetric lens with quadratic phase gradient transformation, combined with the principle of digital coding of metasurface, we propose a wide-angle coded metalens for focusing control in two-dimensional space. This metalens achieves focus shift in the x-direction by changing the oblique incidence angle of the incident wave,and focus control in the y-direction by combining with the convolution principle of the digitally coded metasurface to achieve flexible control of light focusing in the two-dimensional plane. The metasurface unit is mainly composed of threelayer of metal structure and two layers of medium, and the transmission phase is obtained by changing the middle layer of metal structure, which in turn obtains the required phase distribution of the metalens. The design of the metalens realizes the function of the lens with a large viewing angle at the x-polarized incidence, and realizes two-dimensional focus control. Experimentally, we prepared the designed coding metalens and tested the focus control function of the wide-angle coding metalens. The experimental results are in good agreement with the design results.展开更多
Optical metasurfaces are two-dimensional ultrathin devices based on single-layer or multilayer arrays of subwave-length nanostructures. They can achieve precise control of phase, amplitude, and polarization on the sub...Optical metasurfaces are two-dimensional ultrathin devices based on single-layer or multilayer arrays of subwave-length nanostructures. They can achieve precise control of phase, amplitude, and polarization on the subwave-length scale. In this paper, a substrate-free all-silicon coded grating is designed, which can realize the phase control of the outgoing beam after the y-polarized plane wave is vertically incident on the metasurface at 0.1 THz.Through a single-layer silicon nanoarray structure, a low-reflection anomalous transmission metasurface is realized, and a variety of different beam deflectors are designed based on these encoded gratings. We propose a coded grating addition principle, which adds and subtracts two traditional coded grating sequences to obtain a new coded grating sequence. The encoded supergrating can flexibly control the scattering angle, and the designed substrate-free all-silicon encoded grating can achieve a deflection angle of 48.59°. In order to verify the principle of coded grating addition, we experimented with cascade operation of two coded sequence gratings to obtain the flexible control of the terahertz beam of the composite supergrating. The principle of grating addition provides a new degree of freedom for the flexible regulation of the terahertz wavefront. At the same time, this method can be extended to the optical band or microwave band, opening up new ways for electromagnetic wave manipulation and beam scanning.展开更多
The optical regulation strategy of gold nanoparticles can significantly improve the performance of terahertz devices.We designed an all-dielectric double-layer honeycomb metamaterial absorber(MA)to demonstrate the bro...The optical regulation strategy of gold nanoparticles can significantly improve the performance of terahertz devices.We designed an all-dielectric double-layer honeycomb metamaterial absorber(MA)to demonstrate the broadband terahertz absorption characteristics in the presence or absence of gold nanoparticles.When it does not contain gold nanoparticles,MA exhibits a peak absorption efficiency of over 99%within the bandwidth range of∼486 GHz.In particular,gold nanospheres(AuNPs),gold nanobipyramids(AuNBPs),and gold nanorods(AuNRs)are used to modulate the optical coupling effect of metamaterial absorbers,which improves their modulation performance.In the simulation,the effective medium theory(EMT)was applied to quantitatively calculate the optical response of a metamaterial absorber with an integrated gold nanoparticle equivalent gold layer.The integrated gold nanoparticle equivalent gold layer can achieve modulation enhancement of one order of magnitude.In the experiment,our process is compatible with CMOS technology,which may contribute to the development of terahertz detectors.In addition,the tunability and modulation enhancement characteristics demonstrated are beneficial for creating dynamic functional terahertz devices,such as THz modulators and switches.展开更多
Vector beams have attracted widespread attention because of their unique optical properties;in particular,their combination with tight focusing can produce many interesting phenomena.The rise of 3D printing technology...Vector beams have attracted widespread attention because of their unique optical properties;in particular,their combination with tight focusing can produce many interesting phenomena.The rise of 3D printing technology provides more possibilities for exploration.In this work,a cascading method involving a metamaterial and a metalens is used to generate a tightly focused field of vector beams in the terahertz band,which is prepared via 3D printing.As a proof-of-concept demonstration,a series of metamaterial modules capable of generating states of different orbital angular momentum are proposed by cascading with a metalens.The experimental results are in good agreement with the simulation results,fully verifying the feasibility of the scheme.The proposed design and fabrication strategy provides a new idea for the tight focusing of terahertz vector beams.展开更多
基金supported in part by National Natural Science Foundation of China(U24A20307 and 62175224)in part by the science and technology innovation leading talent project of special support plan for high-level talents in Zhejiang Province(2021R52032)+2 种基金in part by the China Jiliang University Basic Research ExpensesZhejiang University Students Science and Technology Innovation Activity Plan-New Talent Plan(2024R409C054)in part by the Natural Science Foundation of Zhejiang Province under Grant(ZCLZ25F0502).
文摘Metasurfaces offer exceptional capabilities for controlling electromagnetic waves,enabling the realization of unique electromagnetic properties.As communication technology continues to evolve,metasurfaces present promising applications in wireless communications.This paper reviews the latest advancements in metasurface research within the communication sector,explores metasurface-based wireless relay technologies,and summarizes various wireless communication methods employing different types of metasurfaces across diverse modulation schemes.This paper provides a detailed discussion on the design of wireless communication systems based on coding metasurfaces to simplify transmitter architecture,as well as the development of intelligent coding metasurfaces in the communication field.It also elaborates on the application of vector vortex light fields in metasurface communication.Finally,it offers a forward-looking perspective on wireless communication systems that incorporate coded metasurfaces.This review aims to furnish researchers with a thorough understanding of the current state and future directions of coded metasurface applications in communications.
基金supported by the Baima Lake Laboratory Joint Fund of the Zhejiang Provincial Natural Science Foundation of China(Grant No.LBMHY25A040002)the National Natural Science Foundation of China(Grant Nos.12304472 and 12304557)+1 种基金the Funds of the Natural Science Foundation of Hangzhou(Grant No.2024SZRYBF050004)the Zhejiang Provincial Natural Science Foundation of China(Grant Nos.ZCLQN25A0401 and ZCLZ25F0502).
文摘The investigation of topological transitions has opened up unprecedented avenues for scientific exploration in photonic metamaterials.However,previous studies mainly focused on exploring different types of three-dimensional(3D)equifrequency surfaces and their topological transition processes in magnetic topological systems.In this work,we study the multiple photonic topological transitions and dual-frequency photonic Weyl points in the topological chiral metamaterials.Through effective medium theory and topological band theory,we systematically characterize and draw comprehensive topological phase diagrams associated with diverse 3D equifrequency surface configurations in nonmagnetic photonic systems.We further demonstrate that the resonance frequencyω0 and dual-frequency Weyl points are the critical points of these topological transitions.Notably,when the vacuum state is in contact with the phases I or III chiral metamaterials,the high-local and frequency chirality-dependent topological Fermi arc surface states arise.We reveal that the parameterωcan be used as a degree of freedom to regulate the bandwidth of such topological surface states.Moreover,different types of multichannel and directional topological photonic routings are achieved using the chirality-dependent Fermi arc surface states.We theoretically show that the physical mechanism of achieving these multichannel topological photonic routings is caused by the different interface properties.We could offer promising perspectives on 3D topological semimetal systems and provide more adaptability for multichannel devices in the nonmagnetic continuous media.
文摘The post-earthquake field investigations reveal that the MW7.9 Wenchuan earthquake of 12th May 2008 ruptured three NE-striking imbricate reverse faults and another NW-trending reverse fault, along the middle Longmenshan fold-and-thrust belt at the eastern margin of the Tibetan plateau. The fault-scarp features can be categorized into eight groups: simple thrust scarp, hanging-wall collapse scarp, simple pressure ridge, dextral pressure ridge, fault-related fold scarp, back-thrust pressure ridge, local normal fault scarp and crocodile-mouth-like scarp. The local normal scarp is first discovered in the reverse-faulting earthquakes as ever reported in the world. Field observation indicates that the Wenchuan earthquake surface rupture is dominated by reverse faulting with a minus right-lateral component, but the relative ratio varies from site to site. Also, the surface ruptures can be divided, for the first order, into two segments, the Yingxiu and Beichuan segments, corresponding to MW7.8 and MW7.57 events, respectively. The two segments further can be divided, for the second order, into four sub-segments in total, which are equivalent to four sub-events of MW7.46, MW7.69, MW6.99 and MW7.52, respectively. The fault segmentation, for different orders, shows a cascade-rupturing pattern and can explain why the quake time of the Wenchuan earthquake was so long as up to 100 second. Aftershock focal mechanisms are also used to constrain the fault geometry for the sub-segments, indicating that the seismogenic faults are listric at depth and in general, the fault plane becomes steeper northward, which enables the fault to accommodate larger strike-slip motion. This earthquake also confirms that the crustal shortening across the Longmenshan fold-and-thrust belt should be responsible for the growth of high topographic relief along the eastern margin of the Tibetan Plateau.
基金supported in part by the Natural Science Foundation of Zhejiang Province under Grant(ZCLZ25F0502)in part by the Science and Technology Innovation Leading Talent Project of Special Support Plan for High-level Talents in Zhejiang Province(2021R52032)+2 种基金in part by the China Jiliang University Basic Research Expensesin part by the Zhejiang University Students Science and Technology Innovation Activity Plan—New Talent Plan(2024R409C054)in part by the Scientific Research Fund of Zhejiang Provincial Education Department(Y202456390).
文摘Metalens is the next generation of optical metasurfaces for compact imaging,sensing,and display applications that allow the phase,polarization,frequency,amplitude,angular momentum,etc.of the incident light to be designed with high degrees of freedom to meet the application requirements,which has attracted broad interest in the field of planar optics.One significant challenge in implementing applications for metalens is the efficient fabrication of largescale nanostructures with high resolution,robustness and uniform patterning.In this review,we first introduced the manufacturing techniques compatible with metasurfaces fabrication in detail,including masked lithography,maskless lithography,and additive manufacturing,discussed the limitations and provided some insights.Next,we introduced the applications of metalens from the perspective of non-imaging and imaging optics fields.Metalens can enhance the illumination effect,shape beams,and improve the energy conversion efficiency in non-imaging optics.In imaging optics,the role of metalens in replacing traditional optical components in lithography,astronomical observation,microscopic and endoscopic systems is demonstrated.Finally,the challenges that the metalens facing on the road to commercial application are discussed,and the field’s future development is prospected.
文摘A brief review of recent progress in researches, productions and applications of full distributed fiber Raman photon sensors at China Jiliang University （CJLU） is presented. In order to improve the measurement distance, the accuracy, the space resolution, the ability of multi-parameter measurements, and the intelligence of full distributed fiber sensor systems, a new generation fiber sensor technology based on the optical fiber nonlinear scattering fusion principle is proposed. A series of new generation full distributed fiber sensors are investigated and designed, which consist of new generation ultra-long distance full distributed fiber Raman and Rayleigh scattering photon sensors integrated with a fiber Raman amplifier, auto-correction full distributed fiber Raman photon temperature sensors based on Raman correlation dual sources, full distributed fiber Raman photon temperature sensors based on a pulse coding source, full distributed fiber Raman photon temperature sensors using a fiber Raman wavelength shifter, a new type of Brillouin optical time domain analyzers （BOTDAs） integrated with a fiber Raman amplifier for replacing a fiber Brillouin amplifier, full distributed fiber Raman and Brillouin photon sensors integrated with a fiber Raman amplifier, and full distributed fiber Brillouin photon sensors integrated with a fiber Brillouin frequency shifter. The Internet of things is believed as one of candidates of the next technological revolution, which has driven hundreds of millions of class markets. Sensor networks are important components of the Internet of things. The full distributed optical fiber sensor network （Rayleigh, Raman, and Brillouin scattering） is a 3S （smart materials, smart structure, and smart skill） system, which is easy to construct smart fiber sensor networks. The distributed optical fiber sensor can be embedded in the power grids, railways, bridges, tunnels, roads, constructions, water supply systems, dams, oil and gas pipelines and other facilities, and can be integrated with wireless networks.
基金This work was supported by the Natu-ral Science Foundation of Zhejiang Province under Grant No.LY20F050007the National Natural Science Foundation of China under Grant No.61875179the National Key Research and De-velopment Project of China under Grant No.2017YFF0206103.
文摘To enhance transmission eficiency of Pancharatnam Berry(PB)phase metasurfaces,multilayer split-ring resonators were proposed to develop encoding sequences.As per the generalized Snell's law,the deflection angle of the PB phase encoding metasurfaces depends on the metasurface period's size.Therefore,it is impossible to design an infinitesimal metasurface unit;consequently,the continuous transmission scattering angle cannot be obtained.In digital signal processing,this study introduces the Fourier convolution principle on encoding metasurface sequences to freely control the trausmitted scattering angles.Both addition and subtraction operations between two diferent encoding sequences were then performed to achieve the continuous variation of the scattering angle.Furthermore,we established that the Fourier convolution principle can be applied to the checkerboard coded metasur-faces.
基金This work was supported by the National Key R&D Program of China(No.2018YFF01013005)the Natural Science Foundation of Zhejiang Province(Nos.LY22F050001,LZ21A040003,and LY20F050007)+2 种基金the National Natural Science Foundation of China(Nos.52076200 and 62175224)the Newshoot Talents Program of Zhejiang province(Nos.2021R409042 and 2021R409012)the Fundamental Research Funds for the Provincial Universities of Zhejiang.
文摘In view of the fact that most invisibility devices focus on linear polarization cloaking and that the characteristics of mid-infrared cloaking are rarely studied,we propose a cross-circularly polarized invisibility carpet cloaking device in the mid-infrared band.Based on the Pancharatnam–Berry phase principle,the unit cells with the cross-circular polarization gradient phase were carefully designed and constructed into a metasurface.In order to achieve tunable cross-circular polarization carpet cloaks,a phase change material is introduced into the design of the unit structure.When the phase change material is in amorphous and crystalline states,the proposed metasurface unit cells can achieve highefficiency cross-polarization conversion,and reflection intensity can be tuned.According to the phase compensation principle of carpet cloaking,we construct a metasurface cloaking device with a phase gradient using the designed unit structure.From the near-and far-field distributions,the cross-circular polarization cloaking property is confirmed in the broadband wavelength range of 9.3–11.4μm.The proposed cloaking device can effectively resist detection of cross-circular polarization.
基金Natural Science Foundation of Zhejiang Province(LY22F050001,LZ21A040003,LY21F050006)National Natural Science Foundation of China(62175224)。
文摘Programmable hyper-coded holography has the advantage of being programmable as well as being flexibly modifiable.Digitally coded metamaterials with excellent electromagnetic modulation capability and the ability to control the phase to modulate the spatial radiation field through external excitation in the form of switching can be used to realize low-cost digital arrays.We design a 1-bit encoded programmable metasurface,which is electrically connected to control the PIN diode in the switching state and to switch the condition of each metasurface cell between“0”and“1.”Using the designed programmable metasurface,we can randomly encode the cell structure to realize single-focus focusing,multi-focusing,and simple holographic letter imaging.Based on the nonlinear holographic model,we employ the Gerchberg-Saxton improvement algorithm to modulate the energy distribution at the focus by adjusting the phase distribution.Importantly,we introduce the Fourier convolution principle to regulate the holographic imaging focus flexibly.
基金supported in part by the Science and technology innovation leading talent project of special support plan for high-level talents in Zhejiang Province(2021R52032)Natural Science Foundation of Zhejiang Province under grant No.LY22F050001+1 种基金Special project for professional degree postgraduates of Zhejiang Provincial Education Department(No.Y202353663,Y202353686)in part by the National Natural Science Foundation of China under grant No.62175224.China Jiliang University Basic Research Expenses.
文摘Based on the principle of super-symmetric lens with quadratic phase gradient transformation, combined with the principle of digital coding of metasurface, we propose a wide-angle coded metalens for focusing control in two-dimensional space. This metalens achieves focus shift in the x-direction by changing the oblique incidence angle of the incident wave,and focus control in the y-direction by combining with the convolution principle of the digitally coded metasurface to achieve flexible control of light focusing in the two-dimensional plane. The metasurface unit is mainly composed of threelayer of metal structure and two layers of medium, and the transmission phase is obtained by changing the middle layer of metal structure, which in turn obtains the required phase distribution of the metalens. The design of the metalens realizes the function of the lens with a large viewing angle at the x-polarized incidence, and realizes two-dimensional focus control. Experimentally, we prepared the designed coding metalens and tested the focus control function of the wide-angle coding metalens. The experimental results are in good agreement with the design results.
基金Natural Science Foundation of Zhejiang Province (LZ21A040003, LY22F050001)National Natural Science Foundation of China (62175224)。
文摘Optical metasurfaces are two-dimensional ultrathin devices based on single-layer or multilayer arrays of subwave-length nanostructures. They can achieve precise control of phase, amplitude, and polarization on the subwave-length scale. In this paper, a substrate-free all-silicon coded grating is designed, which can realize the phase control of the outgoing beam after the y-polarized plane wave is vertically incident on the metasurface at 0.1 THz.Through a single-layer silicon nanoarray structure, a low-reflection anomalous transmission metasurface is realized, and a variety of different beam deflectors are designed based on these encoded gratings. We propose a coded grating addition principle, which adds and subtracts two traditional coded grating sequences to obtain a new coded grating sequence. The encoded supergrating can flexibly control the scattering angle, and the designed substrate-free all-silicon encoded grating can achieve a deflection angle of 48.59°. In order to verify the principle of coded grating addition, we experimented with cascade operation of two coded sequence gratings to obtain the flexible control of the terahertz beam of the composite supergrating. The principle of grating addition provides a new degree of freedom for the flexible regulation of the terahertz wavefront. At the same time, this method can be extended to the optical band or microwave band, opening up new ways for electromagnetic wave manipulation and beam scanning.
基金Science and Technology Innovation Leading Talent Project of Special Support Plan for High-Level Talents(2021R52032)。
文摘The optical regulation strategy of gold nanoparticles can significantly improve the performance of terahertz devices.We designed an all-dielectric double-layer honeycomb metamaterial absorber(MA)to demonstrate the broadband terahertz absorption characteristics in the presence or absence of gold nanoparticles.When it does not contain gold nanoparticles,MA exhibits a peak absorption efficiency of over 99%within the bandwidth range of∼486 GHz.In particular,gold nanospheres(AuNPs),gold nanobipyramids(AuNBPs),and gold nanorods(AuNRs)are used to modulate the optical coupling effect of metamaterial absorbers,which improves their modulation performance.In the simulation,the effective medium theory(EMT)was applied to quantitatively calculate the optical response of a metamaterial absorber with an integrated gold nanoparticle equivalent gold layer.The integrated gold nanoparticle equivalent gold layer can achieve modulation enhancement of one order of magnitude.In the experiment,our process is compatible with CMOS technology,which may contribute to the development of terahertz detectors.In addition,the tunability and modulation enhancement characteristics demonstrated are beneficial for creating dynamic functional terahertz devices,such as THz modulators and switches.
基金This work was supported by the Science and technology innovation leading talent project of special support plan for high-level talents in Zhejiang Province(2021R52032).
文摘Vector beams have attracted widespread attention because of their unique optical properties;in particular,their combination with tight focusing can produce many interesting phenomena.The rise of 3D printing technology provides more possibilities for exploration.In this work,a cascading method involving a metamaterial and a metalens is used to generate a tightly focused field of vector beams in the terahertz band,which is prepared via 3D printing.As a proof-of-concept demonstration,a series of metamaterial modules capable of generating states of different orbital angular momentum are proposed by cascading with a metalens.The experimental results are in good agreement with the simulation results,fully verifying the feasibility of the scheme.The proposed design and fabrication strategy provides a new idea for the tight focusing of terahertz vector beams.
