For an n-variable logic function,the power dissipation and area of the REED-MULLER （RM） circuit corresponding to each polarity are different. Based on the propagation algorithm of signal probability,the decompositio...For an n-variable logic function,the power dissipation and area of the REED-MULLER （RM） circuit corresponding to each polarity are different. Based on the propagation algorithm of signal probability,the decomposition algorithm of a multi-input XOR/AND gate,and the multiple segment algorithm of polarity conversion,this paper successfully applies the whole annealing genetic algorithm （WAGA） to find the best polarity of an RM circuit. Through testing eight large-scale circuits from the Microelectronics Center North Carolina （MCNC） Benchmark, the SYNOPSYS synthesis results show that the RM circuits corresponding to the best polarity found using the proposed algorithm attain average power,area,and max delay savings of 77.2% ,62.4% ,and 9.2% respectively,compared with those under polarity 0.展开更多
Terahertz polarization conversion devices have significant potential applications in various fields such as terahertzimaging and spectroscopy.In this paper,we utilize genetic algorithms to topologically optimize the m...Terahertz polarization conversion devices have significant potential applications in various fields such as terahertzimaging and spectroscopy.In this paper,we utilize genetic algorithms to topologically optimize the metasurface unit cellsand design a reflective linear polarization conversion metasurface with ultra-broadband and wide-angle characteristics.By partitioning the metallic pattern layer into quadrants,the encoding length is effectively reduced,resulting in a shorteroptimization time.The research results indicate that the converter possesses a polarization conversion efficiency ratio higherthan 90%and a relative bandwidth ratio of 125%in a range of 0.231-0.995 THz.Meanwhile,it can maintain excellentpolarization conversion properties when the incident angle of terahertz waves is less than 45°and the polarization angle isless than 15°,demonstrating excellent practicality.New insights are provided for the design of terahertz wide-angle ultrawidebandpolarization conversion devices,and the proposed metasurfce has potential applications in terahertz polarizationimaging,spectroscopy and communication fields.展开更多
Compared with well-developed free space polarization converters, polarization conversion between TE and TM modes in the waveguide is generally considered to be caused by shape birefringence, like curvature, morphology...Compared with well-developed free space polarization converters, polarization conversion between TE and TM modes in the waveguide is generally considered to be caused by shape birefringence, like curvature, morphology of waveguide cross section and scattering. Here, we study the polarization conversion mechanism in 1-THz-FSR X-cut lithium niobate microrings with multiple-resonance condition, that is the conversion can be implemented by birefringence of waveguides,which will also introduce an avoided-mode crossing. In the experiment, we find that this mode crossing results in severe suppression of one sideband in local nondegenerate four-wave mixing and disrupts the cascaded four-wave mixing on this side. Simultaneously, we propose one two-dimensional method to simulate the eigenmodes(TE and TM) in X-cut microrings, and the mode crossing point. This work will provide one approach to the design of polarization converters and simulation for monolithic photonics integrated circuits, and may be helpful to the studies of missed temporal dissipative soliton formation in X-cut lithium niobate rings.展开更多
In this paper,a multifunctional chiral metasurface is presented to achieve asymmetric transmission(AT)and linear-polarization conversion(LPC).The designed metasurface consists of a cross swords-like shape and two hole...In this paper,a multifunctional chiral metasurface is presented to achieve asymmetric transmission(AT)and linear-polarization conversion(LPC).The designed metasurface consists of a cross swords-like shape and two holes in the lower side of the unit cell.In the frequency band from 8.3 GHz to 10.4 GHz,AT is realized with more than 90%efficiency and the same chiral metasurface transforms linear polarized wave into its orthogonal counterpart with high efficiency.For LPC,the polarization conversion ratio(PCR)is greater than 95%.The proposed metasurface is stable against the incident angles of striking electromagnetic(EM)waves up to 60°for both operations of AT and LPC.展开更多
A polarization converter with broadband polarization characteristics and capable of dynamic reconfiguration is proposed.By introducing out-of-plane degrees of freedom,dynamically tunable broadband and high-efficiency ...A polarization converter with broadband polarization characteristics and capable of dynamic reconfiguration is proposed.By introducing out-of-plane degrees of freedom,dynamically tunable broadband and high-efficiency linear polarization conversion within the wavelength range of 2000-2800 nm is achieved.Research results indicate that when a two-dimensional(2D)split-ring resonator(SRR)is irradiated by a low-dose focused ion beam,it will deform upward and transform into a three-dimensional(3D)SRR,achieving a linear polarization conversion efficiency of over 90%.The 3D SRR can be driven by electrostatic force to return to the 2D SRR state,thereby realizing the dynamic reconfiguration of this polarization converter.By changing the applied voltage and adjusting the structural parameters,a tailored polarization converter that exhibits broadband performance and high polarization conversion efficiency is also achieved.The results may provide novel ideas and technical methodologies for various applications such as polarized optical imaging,emerging display technologies,polarized optical communication,and optical sensing.展开更多
The terahertz(THz)resonance,chirality,and polarization conversion properties of a double-layer chiral metasurface have been experimentally investigated by THz time domain spectroscopy system and polarization detection...The terahertz(THz)resonance,chirality,and polarization conversion properties of a double-layer chiral metasurface have been experimentally investigated by THz time domain spectroscopy system and polarization detection method.The special symmetric geometry of each unit cell with its adjacent cells makes a strong chiral electromagnetic response in this metasurface,which leads to a strong polarization conversion effect.Moreover,compared with the traditional THz transmission resonance sensing for film thickness,the polarization sensing characterized by polarization elliptical angle(PEA)and polarization rotation angle(PRA)shows a better Q factor and figure of merit(FoM).The results show that the Q factors of the PEA and PRA reach 43.8 and 49.1 when the interval film is 20µm,while the Q factor of THz resonance sensing is only 10.6.And these PEA and PRA can play a complementary role to obtain a double-parameter sensing method with a higher FoM,over 4 times than that of resonance sensing.This chiral metasurface and its polarization sensing method provide new ideas for the development of high-efficiency THz polarization manipulation,and open a window to the high sensitive sensing by using THz polarization spectroscopy.展开更多
We propose a broadband perfect polarization conversion metasurface composed of copper sheet-backed asymmetric double spilt ring resonator（DSRR）. The broadband perfect polarization convertibility results from metalli...We propose a broadband perfect polarization conversion metasurface composed of copper sheet-backed asymmetric double spilt ring resonator（DSRR）. The broadband perfect polarization convertibility results from metallic ground and multiple plasmon resonances of the DSRR. Physics of plasmon resonances are governed by the electric and magnetic resonances. Both the simulation and measured results show that the polarization conversion ratio（PCR） is higher than 99%for both x- and y-polarized normally incident EM waves and the fractional bandwidth is about 34.5%. The metasurface possesses the merits of high PCR and broad bandwidth, and thus has great application values in novel polarization-control devices.展开更多
We present a transmission-type polarization conversion metamaterial(PCM)whose functions can be dynamically switched among the linear-to-circular(LTC)and linear-to-linear(LTL)polarization conversions.The proposed PCM c...We present a transmission-type polarization conversion metamaterial(PCM)whose functions can be dynamically switched among the linear-to-circular(LTC)and linear-to-linear(LTL)polarization conversions.The proposed PCM consists of a grating,a polarization conversion surface and a reconfigurable polarization selective surface incorporated with PIN diodes.By changing the states of diodes,the PCM can achieve the reconfigurable manipulations for incident waves.The Fabry-Pérot(F-P)resonances excited by the PCM contribute to the polarization conversions,as is illustrated.Moreover,through establishing the F-P-like cavity model and analyzing the electric field components of the transmitted waves,the conditions for realizing LTC polarization conversion are revealed,which can guide the construction of PCM.The prototype of PCM is fabricated and measured,which can achieve LTC and LTL polarization conversions within 3.31-3.56 GHz and 2.76-4.24 GHz,respectively,the polarization conversion ratios of two functions are higher than 0.95.The measurement results are in agreement with the simulation data.展开更多
Simultaneous broadband absorption and polarization conversion are crucial in many practical applications,especially in terahertz communications.Thus,actively tunable metamaterial systems can exploit the graphene-based...Simultaneous broadband absorption and polarization conversion are crucial in many practical applications,especially in terahertz communications.Thus,actively tunable metamaterial systems can exploit the graphene-based nanomaterials derived from renewable resources because of the flexible surface conductivity and selective permeability of the nanomaterials at terahertz frequencies.In this paper,we propose a graphene-based active tunable bifunctional metasurface for dynamic terahertz absorption and polarization conversion.The graphene ring presents a certain opening angle(A)along the diagonal of the xoy plane.When A=0°,the proposed metasurface behaves as a broadband absorber.Numerical results show the feasibility of achieving this polarization-insensitive absorber with nearly 100%absorptance,and the bandwidth of its 90%absorptance is 1.22 THz under normal incidence.Alternatively,when A=40°after optimization,the proposed metasurface serves as a broadband polarization convertor,resulting in robust broadband polarization conversion ratio(PCR)curves with a bandwidth surpassing 0.5 THz in the reflection spectrum.To tune the PCR response or the broad absorption spectrum of graphene,we change the Fermi energy of graphene dynamically from 0 to 0.9 eV.Furthermore,both the broadband absorption and the linear polarization conversion spectra of the proposed metasurface exhibit insensitivity to the incident angle,allowing large incident angles within 40°under high-performance operating conditions.To demonstrate the physical process,we present the impedance matching theory and measure electric field distributions.This architecture in the THz frequency range has several applications,such as in modulators,sensors,stealth,and optoelectronic switches.THz wave polarization and beam steering also have broad application prospects in the field of intelligent systems.展开更多
Polarization conversion is a very important electromagnetic wave manipulation method.In this paper,we investigate a high-efficiency linear-to-circular polarization and cross-polarization converter by utilizing coding ...Polarization conversion is a very important electromagnetic wave manipulation method.In this paper,we investigate a high-efficiency linear-to-circular polarization and cross-polarization converter by utilizing coding metasurface.The coding particle consists of top layer metal pattern and bottom metal plate sandwiched with square F4B dielectric,which can manipulate the linear-to-circular polarization and cross-polarization converter of the reflected wave simultaneously.In the terahertz frequency range of 1.0 THz-2.0 THz,the reflection magnitudes reach approximately 90%and the axial ratio is less than 3 dB.The proposed polarization converter may lead to advances in a variety of applications such as security,microscopy,information processing,stealth technology,and data storage.展开更多
An ultra-wideband and high-efficiency reflective linear-to-circular polarization conversion metasurface is proposed. The proposed metasurface is composed of a square array of a corner-truncated square patch printed on...An ultra-wideband and high-efficiency reflective linear-to-circular polarization conversion metasurface is proposed. The proposed metasurface is composed of a square array of a corner-truncated square patch printed on grounded dielectric substrate and covered with a dielectric layer, which is an orthotropic anisotropic structure with a pair of mutually perpendicular symmetric axes u and v along the directions with the tilt angles of ±45° with respect to the vertical y axis. When the u- and v-polarized waves are incident on the proposed metasurface, the phase difference between the two reflection coefficients is close to –90° in an ultra-wide frequency band, so it can realize high-efficiency and ultra-wideband LTC polarization conversion under both x- and y-polarized incidences in this band. The proposed polarization conversion metasurface is simulated and measured. Both the simulated and measured results show that the axial ratio (AR) of the reflected wave is kept below 3 dB in the ultra-wide frequency band of 5.87 GHz–21.13 GHz, which is corresponding to a relative bandwidth of 113%;moreover, the polarization conversion rate (PCR) can be kept larger than 99% in a frequency range of 8.08 GHz–20.92 GHz.展开更多
Resonant responses of metasurface enable effective control over the polarization properties of lights. In this paper,we demonstrate a double-rod metasurface for broadband polarization conversion in the mid-infrared re...Resonant responses of metasurface enable effective control over the polarization properties of lights. In this paper,we demonstrate a double-rod metasurface for broadband polarization conversion in the mid-infrared region. The metasurface consists of a metallic double-rod array separated from a reflecting ground plane by a film of zinc selenide. By superimposing three localized resonances, cross polarization conversion is achieved over a bandwidth of 16.9 THz around the central frequency at 34.6 THz with conversion efficiency exceeding 70%. The polarization conversion performance is in qualitative agreement with simulation. The surface current distributions and electric field profiles of the resonant modes are discussed to analyze the underlying physical mechanism. Our demonstrated broadband polarization conversion has potential applications in the area of mid-infrared spectroscopy, communication, and sensing.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
Recently,polarization conversion based on the equivalent magnetic field of Weyl semimetals(WSMs)has gained significant attention.Based on a twin WSM-layer structure,we transplant the concept of twist from Twistronics ...Recently,polarization conversion based on the equivalent magnetic field of Weyl semimetals(WSMs)has gained significant attention.Based on a twin WSM-layer structure,we transplant the concept of twist from Twistronics to obtain a dynamically tunable polarization converter with multifunctions and nonreciprocity.One-way conversion of linear polarization to its orthogonal state can be obtained and tuned by twisting the converter.Moreover,nonreciprocal conversion from linear polarization to elliptical polarization(with ellipticity linearly tuned from-1 to 1 by twisting the converter)in one way and to quasi-linear polarization in the other way can be obtained.Calculations show that the converter achieves 95%efficiency,high optical isolation(100 d B),and low insertion loss(<2 d B).The proposal may find applications in tunable and nonreciprocal devices for integrated photonics.展开更多
In active reconfigurable polarization conversion metasurfaces,the integration of electromagnetic radiation performance and heat dissipation efficiency presents two critical challenges.In this work,we proposed a graphe...In active reconfigurable polarization conversion metasurfaces,the integration of electromagnetic radiation performance and heat dissipation efficiency presents two critical challenges.In this work,we proposed a graphene-based reconfigurable polarization metasurface that integrates heat dissipation and electromagnetic regulation functions.The proposed graphene metasurface modulates the polarization state of the reflected wave at multiple frequency bands via the on-off switching of PIN diodes.When the PIN diode is in the ON state,the metaurface can modulate the incident linear polarization wave into its cross-polarization wave in 5.73-6.15 and 11.25-13.10 GHz,and into a circular polarization wave in 6.27-10.18 GHz.When the PIN diode is switched to the off state,the cross-polarization transitions are achieved in 5.75-7.32 and 12.83-14.24 GHz,with full reflection in the band of 7.92-10.15 GHz,and circular polarization in 12.83-14.24 GHz.In addition,when the graphene metasurface system worked after a long period of operation,the temperature of the graphene metasurface is 21.3℃,which is 34.2℃lower than that of the copper metasurface,this has less impact on the temperature drift effect of the PIN diode.The integrated graphene polarized reconfigurable metasurface for radiation and heat dissipation addresses the performance,volume,and thermal management limitations of traditional systems through multifunctional integration and dynamic tunability,offering significant potential for future smart electromagnetic devices application in communication,radar,and Internet of Things.展开更多
A novel and practical synthetic route is presented for the preparation of methyl-（E）-2-（3-（3-（2-（7-chloro-2-quinolinyl）ethenyl） phenyl）-3-oxopropyl）benzoate,the key intermediate of Montelukast,a leukotriene ...A novel and practical synthetic route is presented for the preparation of methyl-（E）-2-（3-（3-（2-（7-chloro-2-quinolinyl）ethenyl） phenyl）-3-oxopropyl）benzoate,the key intermediate of Montelukast,a leukotriene antagonist.The main diarylpropane framework was prepared via a polarity conversation reaction resulting in an acyl anion equivalent followed by a nucleophilic substitution reaction.The overall yield of this approach was 61%.This method is simple for operation and suitable for industrial production.展开更多
We proposed a sandwich structure to realize broadband asymmetric transmission(AT) for both linearly and circularly polarized waves in the near infrared spectral region. The structure composes of a silica substrate and...We proposed a sandwich structure to realize broadband asymmetric transmission(AT) for both linearly and circularly polarized waves in the near infrared spectral region. The structure composes of a silica substrate and two sand-clock-like gold layers on the opposite sides of the substrate. Due to the surface plasmons of gold, the structure shows that the AT parameters of linearly and circularly polarized waves can reach 0.436 and 0.403, respectively. Meanwhile, a broadband property is presented for the AT parameter is over 0.3 between 320 THz and 340 THz. The structure realizes a diode-like AT for linearly wave in forward and circularly wave in backward, respectively. The magnetic dipoles excited by current in the two gold layers contribute to the broadband AT. The current density in top and bottom metallic layers illustrates the mechanism of the polarization conversion for broadband AT in detail.展开更多
The terahertz technology has attracted considerable attention because of its potential applications in various fields.However,the research of functional devices,including polarization converters,remains a major demand...The terahertz technology has attracted considerable attention because of its potential applications in various fields.However,the research of functional devices,including polarization converters,remains a major demand for practical applications.In this work,a reflective dual-functional terahertz metadevice is presented,which combines two different polarization conversions through using a switchable metasurface.Different functions can be achieved because of the insulator-to-metal transition of vanadium dioxide(VO_(2)).At room temperature,the metadevice can be regarded as a linear-to-linear polarization convertor containing a gold circular split-ring resonator(CSRR),first polyimide(PI)spacer,continuous VO_(2) film,second PI spacer,and gold substrate.The converter possesses a polarization conversion ratio higher than 0.9 and a bandwidth ratio of 81%in a range from 0.912 THz to 2.146 THz.When the temperature is above the insulator-to-metal transition temperature(approximately 68℃)and VO_(2) becomes a metal,the metasurface transforms into a wideband linear-to-circular polarization converter composed of the gold CSRR,first PI layer,and continuous VO_(2) film.The ellipticity is close to-1,while the axis ratio is lower than 3 dB in a range of 1.07 THz-1.67 THz.The metadevice also achieves a large angle tolerance and large manufacturing tolerance.展开更多
This study proposes a bi-layer windmill-shaped metamaterial that consists of resonators, with similar shapes, on both sides of a dielectric substrate. In this study, the second layer is rotated clockwise around the su...This study proposes a bi-layer windmill-shaped metamaterial that consists of resonators, with similar shapes, on both sides of a dielectric substrate. In this study, the second layer is rotated clockwise around the substrate normal at 90°and thereafter flipped in the first layer. Due to the introduction of a windmill-like shape, the resonant structures result in new resonant modes and thus can achieve multi-band high-efficiency cross-polarization conversions and asymmetric transmissions(ATs) for a linearly polarized incident plane wave with a maximum asymmetric parameter of 0.72. Depending on the geometric parameters of our windmill-shaped structures, the AT effects can be flexibly modulated in a broad multiband from 160 THz to 400 THz, which has not been reported in previous studies. These outstanding AT effects provide potential applications in optical diodes, polarization control switches, and other nano-devices.展开更多
A three-dimensional chiral metamaterial with four-fold rotational symmetry is designed, and its optical properties are investigated by numerical simulations. The results show that this chiral metamaterial has the foll...A three-dimensional chiral metamaterial with four-fold rotational symmetry is designed, and its optical properties are investigated by numerical simulations. The results show that this chiral metamaterial has the following features：high polarization conversion, perfect circular dichroism, and asymmetric transmission of circularly polarized light. A comparison of the results of chiral metamaterials without and with weak coupling between the constituent nanostructures enables us to confirm that the optical properties of our proposed nanostructure are closely related to the coupling between the single nanoparticles. This means that the coupling between nanoparticles can enhance the polarization conversion, circular dichroism, and asymmetric transmission. Due to the excellent optical properties, our metamaterial might have potential applications in the development of future multi-functional optical devices.展开更多
文摘For an n-variable logic function,the power dissipation and area of the REED-MULLER （RM） circuit corresponding to each polarity are different. Based on the propagation algorithm of signal probability,the decomposition algorithm of a multi-input XOR/AND gate,and the multiple segment algorithm of polarity conversion,this paper successfully applies the whole annealing genetic algorithm （WAGA） to find the best polarity of an RM circuit. Through testing eight large-scale circuits from the Microelectronics Center North Carolina （MCNC） Benchmark, the SYNOPSYS synthesis results show that the RM circuits corresponding to the best polarity found using the proposed algorithm attain average power,area,and max delay savings of 77.2% ,62.4% ,and 9.2% respectively,compared with those under polarity 0.
基金supported by the National Natural Science Foundation of China and the Open Project Program of Wuhan National Laboratory for Optoelectronics(Grant No.2022WNLOKF012).
文摘Terahertz polarization conversion devices have significant potential applications in various fields such as terahertzimaging and spectroscopy.In this paper,we utilize genetic algorithms to topologically optimize the metasurface unit cellsand design a reflective linear polarization conversion metasurface with ultra-broadband and wide-angle characteristics.By partitioning the metallic pattern layer into quadrants,the encoding length is effectively reduced,resulting in a shorteroptimization time.The research results indicate that the converter possesses a polarization conversion efficiency ratio higherthan 90%and a relative bandwidth ratio of 125%in a range of 0.231-0.995 THz.Meanwhile,it can maintain excellentpolarization conversion properties when the incident angle of terahertz waves is less than 45°and the polarization angle isless than 15°,demonstrating excellent practicality.New insights are provided for the design of terahertz wide-angle ultrawidebandpolarization conversion devices,and the proposed metasurfce has potential applications in terahertz polarizationimaging,spectroscopy and communication fields.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12274462 and 11674396)the Department of Science and Technology of Hunan Province of China (Grant Nos. 2017RS3039 and 2018JJ1033)the Hunan Provincial Innovation Foundation for Postgraduate of China (Grant No. QL20210006)。
文摘Compared with well-developed free space polarization converters, polarization conversion between TE and TM modes in the waveguide is generally considered to be caused by shape birefringence, like curvature, morphology of waveguide cross section and scattering. Here, we study the polarization conversion mechanism in 1-THz-FSR X-cut lithium niobate microrings with multiple-resonance condition, that is the conversion can be implemented by birefringence of waveguides,which will also introduce an avoided-mode crossing. In the experiment, we find that this mode crossing results in severe suppression of one sideband in local nondegenerate four-wave mixing and disrupts the cascaded four-wave mixing on this side. Simultaneously, we propose one two-dimensional method to simulate the eigenmodes(TE and TM) in X-cut microrings, and the mode crossing point. This work will provide one approach to the design of polarization converters and simulation for monolithic photonics integrated circuits, and may be helpful to the studies of missed temporal dissipative soliton formation in X-cut lithium niobate rings.
文摘In this paper,a multifunctional chiral metasurface is presented to achieve asymmetric transmission(AT)and linear-polarization conversion(LPC).The designed metasurface consists of a cross swords-like shape and two holes in the lower side of the unit cell.In the frequency band from 8.3 GHz to 10.4 GHz,AT is realized with more than 90%efficiency and the same chiral metasurface transforms linear polarized wave into its orthogonal counterpart with high efficiency.For LPC,the polarization conversion ratio(PCR)is greater than 95%.The proposed metasurface is stable against the incident angles of striking electromagnetic(EM)waves up to 60°for both operations of AT and LPC.
基金supported by the National Natural Science Foundation of China(Nos.T2325005,62375016,62475250)the Science and Technology Project of Guangdong(No.2020B010190001)。
文摘A polarization converter with broadband polarization characteristics and capable of dynamic reconfiguration is proposed.By introducing out-of-plane degrees of freedom,dynamically tunable broadband and high-efficiency linear polarization conversion within the wavelength range of 2000-2800 nm is achieved.Research results indicate that when a two-dimensional(2D)split-ring resonator(SRR)is irradiated by a low-dose focused ion beam,it will deform upward and transform into a three-dimensional(3D)SRR,achieving a linear polarization conversion efficiency of over 90%.The 3D SRR can be driven by electrostatic force to return to the 2D SRR state,thereby realizing the dynamic reconfiguration of this polarization converter.By changing the applied voltage and adjusting the structural parameters,a tailored polarization converter that exhibits broadband performance and high polarization conversion efficiency is also achieved.The results may provide novel ideas and technical methodologies for various applications such as polarized optical imaging,emerging display technologies,polarized optical communication,and optical sensing.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0701000)the National Natural Science Foundation of China(Grant Nos.61971242,61831012,and 61671491)+1 种基金the Natural Science Foundation of Tianjin City,China(Grant No.19JCYBJC16600)the Young Elite Scientists Sponsorship Program by Tianjin,China(Grant No.TJSQNTJ-2017-12).
文摘The terahertz(THz)resonance,chirality,and polarization conversion properties of a double-layer chiral metasurface have been experimentally investigated by THz time domain spectroscopy system and polarization detection method.The special symmetric geometry of each unit cell with its adjacent cells makes a strong chiral electromagnetic response in this metasurface,which leads to a strong polarization conversion effect.Moreover,compared with the traditional THz transmission resonance sensing for film thickness,the polarization sensing characterized by polarization elliptical angle(PEA)and polarization rotation angle(PRA)shows a better Q factor and figure of merit(FoM).The results show that the Q factors of the PEA and PRA reach 43.8 and 49.1 when the interval film is 20µm,while the Q factor of THz resonance sensing is only 10.6.And these PEA and PRA can play a complementary role to obtain a double-parameter sensing method with a higher FoM,over 4 times than that of resonance sensing.This chiral metasurface and its polarization sensing method provide new ideas for the development of high-efficiency THz polarization manipulation,and open a window to the high sensitive sensing by using THz polarization spectroscopy.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61331005,11204378,11274389,11304393,and 61302023)the National Science Foundation for Post-doctoral Scientists of China(Grant Nos.2013M532131 and 2013M532221)+1 种基金the Natural Science Foundation of Shaanxi Province,China(Grant No.2013JM6005)the Aviation Science Foundation of China(Grant Nos.20132796018 and 20123196015)
文摘We propose a broadband perfect polarization conversion metasurface composed of copper sheet-backed asymmetric double spilt ring resonator（DSRR）. The broadband perfect polarization convertibility results from metallic ground and multiple plasmon resonances of the DSRR. Physics of plasmon resonances are governed by the electric and magnetic resonances. Both the simulation and measured results show that the polarization conversion ratio（PCR） is higher than 99%for both x- and y-polarized normally incident EM waves and the fractional bandwidth is about 34.5%. The metasurface possesses the merits of high PCR and broad bandwidth, and thus has great application values in novel polarization-control devices.
基金Project supported by the Fundamental Research Funds for Central Universities(Grant No.2682020GF03)
文摘We present a transmission-type polarization conversion metamaterial(PCM)whose functions can be dynamically switched among the linear-to-circular(LTC)and linear-to-linear(LTL)polarization conversions.The proposed PCM consists of a grating,a polarization conversion surface and a reconfigurable polarization selective surface incorporated with PIN diodes.By changing the states of diodes,the PCM can achieve the reconfigurable manipulations for incident waves.The Fabry-Pérot(F-P)resonances excited by the PCM contribute to the polarization conversions,as is illustrated.Moreover,through establishing the F-P-like cavity model and analyzing the electric field components of the transmitted waves,the conditions for realizing LTC polarization conversion are revealed,which can guide the construction of PCM.The prototype of PCM is fabricated and measured,which can achieve LTC and LTL polarization conversions within 3.31-3.56 GHz and 2.76-4.24 GHz,respectively,the polarization conversion ratios of two functions are higher than 0.95.The measurement results are in agreement with the simulation data.
基金supported by the High Level Talent Project of Basic and Applied Basic Research(Natural Science)of Hainan Province in 2019(No.2019RC158)by the Project of the Education Department of Hainan Province(No.Hnky2020ZD-2),all support is gratefully acknowledged.
文摘Simultaneous broadband absorption and polarization conversion are crucial in many practical applications,especially in terahertz communications.Thus,actively tunable metamaterial systems can exploit the graphene-based nanomaterials derived from renewable resources because of the flexible surface conductivity and selective permeability of the nanomaterials at terahertz frequencies.In this paper,we propose a graphene-based active tunable bifunctional metasurface for dynamic terahertz absorption and polarization conversion.The graphene ring presents a certain opening angle(A)along the diagonal of the xoy plane.When A=0°,the proposed metasurface behaves as a broadband absorber.Numerical results show the feasibility of achieving this polarization-insensitive absorber with nearly 100%absorptance,and the bandwidth of its 90%absorptance is 1.22 THz under normal incidence.Alternatively,when A=40°after optimization,the proposed metasurface serves as a broadband polarization convertor,resulting in robust broadband polarization conversion ratio(PCR)curves with a bandwidth surpassing 0.5 THz in the reflection spectrum.To tune the PCR response or the broad absorption spectrum of graphene,we change the Fermi energy of graphene dynamically from 0 to 0.9 eV.Furthermore,both the broadband absorption and the linear polarization conversion spectra of the proposed metasurface exhibit insensitivity to the incident angle,allowing large incident angles within 40°under high-performance operating conditions.To demonstrate the physical process,we present the impedance matching theory and measure electric field distributions.This architecture in the THz frequency range has several applications,such as in modulators,sensors,stealth,and optoelectronic switches.THz wave polarization and beam steering also have broad application prospects in the field of intelligent systems.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFF0200306)the National Natural Science Foundation of China(Grant Nos.61871355 and 61831012).
文摘Polarization conversion is a very important electromagnetic wave manipulation method.In this paper,we investigate a high-efficiency linear-to-circular polarization and cross-polarization converter by utilizing coding metasurface.The coding particle consists of top layer metal pattern and bottom metal plate sandwiched with square F4B dielectric,which can manipulate the linear-to-circular polarization and cross-polarization converter of the reflected wave simultaneously.In the terahertz frequency range of 1.0 THz-2.0 THz,the reflection magnitudes reach approximately 90%and the axial ratio is less than 3 dB.The proposed polarization converter may lead to advances in a variety of applications such as security,microscopy,information processing,stealth technology,and data storage.
基金Project supported by the Natural Science Foundation of Shaanxi Province, China (Grant Nos. 2019JM-077 and 2018JM-6098)the Scientific Research Program Funded by Shaanxi Provincial Education Department (Grant No. 18JK1195)the Shaanxi Key Research and Development Project, China (Grant No. 2019GY-055).
文摘An ultra-wideband and high-efficiency reflective linear-to-circular polarization conversion metasurface is proposed. The proposed metasurface is composed of a square array of a corner-truncated square patch printed on grounded dielectric substrate and covered with a dielectric layer, which is an orthotropic anisotropic structure with a pair of mutually perpendicular symmetric axes u and v along the directions with the tilt angles of ±45° with respect to the vertical y axis. When the u- and v-polarized waves are incident on the proposed metasurface, the phase difference between the two reflection coefficients is close to –90° in an ultra-wide frequency band, so it can realize high-efficiency and ultra-wideband LTC polarization conversion under both x- and y-polarized incidences in this band. The proposed polarization conversion metasurface is simulated and measured. Both the simulated and measured results show that the axial ratio (AR) of the reflected wave is kept below 3 dB in the ultra-wide frequency band of 5.87 GHz–21.13 GHz, which is corresponding to a relative bandwidth of 113%;moreover, the polarization conversion rate (PCR) can be kept larger than 99% in a frequency range of 8.08 GHz–20.92 GHz.
基金Project supported by the National Natural Science Foundation of China(Grants Nos.61421002 and 61575036)the Chinese National 1000 Plan for Young Talentsthe Startup Funding from University of Electronic Science and Technology of China
文摘Resonant responses of metasurface enable effective control over the polarization properties of lights. In this paper,we demonstrate a double-rod metasurface for broadband polarization conversion in the mid-infrared region. The metasurface consists of a metallic double-rod array separated from a reflecting ground plane by a film of zinc selenide. By superimposing three localized resonances, cross polarization conversion is achieved over a bandwidth of 16.9 THz around the central frequency at 34.6 THz with conversion efficiency exceeding 70%. The polarization conversion performance is in qualitative agreement with simulation. The surface current distributions and electric field profiles of the resonant modes are discussed to analyze the underlying physical mechanism. Our demonstrated broadband polarization conversion has potential applications in the area of mid-infrared spectroscopy, communication, and sensing.
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supported by the Guangdong Provincial Key Laboratory(No.2020B1212060066)。
文摘Recently,polarization conversion based on the equivalent magnetic field of Weyl semimetals(WSMs)has gained significant attention.Based on a twin WSM-layer structure,we transplant the concept of twist from Twistronics to obtain a dynamically tunable polarization converter with multifunctions and nonreciprocity.One-way conversion of linear polarization to its orthogonal state can be obtained and tuned by twisting the converter.Moreover,nonreciprocal conversion from linear polarization to elliptical polarization(with ellipticity linearly tuned from-1 to 1 by twisting the converter)in one way and to quasi-linear polarization in the other way can be obtained.Calculations show that the converter achieves 95%efficiency,high optical isolation(100 d B),and low insertion loss(<2 d B).The proposal may find applications in tunable and nonreciprocal devices for integrated photonics.
基金supported by the National Natural Science Foundation of China(No.51672204)Hubei Provincial Natural Science Foundation of China(No.2025AFB082).
文摘In active reconfigurable polarization conversion metasurfaces,the integration of electromagnetic radiation performance and heat dissipation efficiency presents two critical challenges.In this work,we proposed a graphene-based reconfigurable polarization metasurface that integrates heat dissipation and electromagnetic regulation functions.The proposed graphene metasurface modulates the polarization state of the reflected wave at multiple frequency bands via the on-off switching of PIN diodes.When the PIN diode is in the ON state,the metaurface can modulate the incident linear polarization wave into its cross-polarization wave in 5.73-6.15 and 11.25-13.10 GHz,and into a circular polarization wave in 6.27-10.18 GHz.When the PIN diode is switched to the off state,the cross-polarization transitions are achieved in 5.75-7.32 and 12.83-14.24 GHz,with full reflection in the band of 7.92-10.15 GHz,and circular polarization in 12.83-14.24 GHz.In addition,when the graphene metasurface system worked after a long period of operation,the temperature of the graphene metasurface is 21.3℃,which is 34.2℃lower than that of the copper metasurface,this has less impact on the temperature drift effect of the PIN diode.The integrated graphene polarized reconfigurable metasurface for radiation and heat dissipation addresses the performance,volume,and thermal management limitations of traditional systems through multifunctional integration and dynamic tunability,offering significant potential for future smart electromagnetic devices application in communication,radar,and Internet of Things.
基金supported by the National Key Project for Basic Research(No2010CB1126102)the Outstanding Youth Foundation of Heilongjiang Province(NoJC200706)
文摘A novel and practical synthetic route is presented for the preparation of methyl-（E）-2-（3-（3-（2-（7-chloro-2-quinolinyl）ethenyl） phenyl）-3-oxopropyl）benzoate,the key intermediate of Montelukast,a leukotriene antagonist.The main diarylpropane framework was prepared via a polarity conversation reaction resulting in an acyl anion equivalent followed by a nucleophilic substitution reaction.The overall yield of this approach was 61%.This method is simple for operation and suitable for industrial production.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11965009,61874036,61805053,and 61764001)the Natural Science Foundation of Guangxi Zhuang Autonomous Region,China(Grant Nos.2018JJA170010 and 2018GXNSFAA281193)the Innovation Project of GUET Graduate Education(Grant No.2020YCXS019)。
文摘We proposed a sandwich structure to realize broadband asymmetric transmission(AT) for both linearly and circularly polarized waves in the near infrared spectral region. The structure composes of a silica substrate and two sand-clock-like gold layers on the opposite sides of the substrate. Due to the surface plasmons of gold, the structure shows that the AT parameters of linearly and circularly polarized waves can reach 0.436 and 0.403, respectively. Meanwhile, a broadband property is presented for the AT parameter is over 0.3 between 320 THz and 340 THz. The structure realizes a diode-like AT for linearly wave in forward and circularly wave in backward, respectively. The magnetic dipoles excited by current in the two gold layers contribute to the broadband AT. The current density in top and bottom metallic layers illustrates the mechanism of the polarization conversion for broadband AT in detail.
基金the National Natural Science Foundation of China(Grant No.62001444)the Natural Science Foundation of Zhejiang Province,China(Grant No.LQ20F010009)+1 种基金the Basic Public Welfare Research Project of Zhejiang Province,China(Grant No.LGF19F010003)the State Key Laboratory of Crystal Materials,Shandong University,China(Grant No.KF1909)。
文摘The terahertz technology has attracted considerable attention because of its potential applications in various fields.However,the research of functional devices,including polarization converters,remains a major demand for practical applications.In this work,a reflective dual-functional terahertz metadevice is presented,which combines two different polarization conversions through using a switchable metasurface.Different functions can be achieved because of the insulator-to-metal transition of vanadium dioxide(VO_(2)).At room temperature,the metadevice can be regarded as a linear-to-linear polarization convertor containing a gold circular split-ring resonator(CSRR),first polyimide(PI)spacer,continuous VO_(2) film,second PI spacer,and gold substrate.The converter possesses a polarization conversion ratio higher than 0.9 and a bandwidth ratio of 81%in a range from 0.912 THz to 2.146 THz.When the temperature is above the insulator-to-metal transition temperature(approximately 68℃)and VO_(2) becomes a metal,the metasurface transforms into a wideband linear-to-circular polarization converter composed of the gold CSRR,first PI layer,and continuous VO_(2) film.The ellipticity is close to-1,while the axis ratio is lower than 3 dB in a range of 1.07 THz-1.67 THz.The metadevice also achieves a large angle tolerance and large manufacturing tolerance.
基金Project supported by the National Youth Foundation of China(Grant Nos.11904200 and 11704219)the National Natural Science Foundation of China(Grant No.11774053)+3 种基金the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20190726)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant No.18KJD140004)NJUPT-SF(Grant No.NY218099)the Opening Project of the Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology(Grant No.hxkj2019007).
文摘This study proposes a bi-layer windmill-shaped metamaterial that consists of resonators, with similar shapes, on both sides of a dielectric substrate. In this study, the second layer is rotated clockwise around the substrate normal at 90°and thereafter flipped in the first layer. Due to the introduction of a windmill-like shape, the resonant structures result in new resonant modes and thus can achieve multi-band high-efficiency cross-polarization conversions and asymmetric transmissions(ATs) for a linearly polarized incident plane wave with a maximum asymmetric parameter of 0.72. Depending on the geometric parameters of our windmill-shaped structures, the AT effects can be flexibly modulated in a broad multiband from 160 THz to 400 THz, which has not been reported in previous studies. These outstanding AT effects provide potential applications in optical diodes, polarization control switches, and other nano-devices.
基金Project supported by the National Natural Science Foundation of China(Grant No.11304002)the Natural Science Foundation of Education Bureau of Anhui Province,China(Grant No.KJ2013A136)the Natural Science Foundation of Anhui Province,China(Grant No.1208085MA07)
文摘A three-dimensional chiral metamaterial with four-fold rotational symmetry is designed, and its optical properties are investigated by numerical simulations. The results show that this chiral metamaterial has the following features：high polarization conversion, perfect circular dichroism, and asymmetric transmission of circularly polarized light. A comparison of the results of chiral metamaterials without and with weak coupling between the constituent nanostructures enables us to confirm that the optical properties of our proposed nanostructure are closely related to the coupling between the single nanoparticles. This means that the coupling between nanoparticles can enhance the polarization conversion, circular dichroism, and asymmetric transmission. Due to the excellent optical properties, our metamaterial might have potential applications in the development of future multi-functional optical devices.
