We theoretically and numerically demonstrate that a transmission-type electrically tunable polarizer can be realized by using graphene ribbons supported on a dielectric film with a graphene sheet behind. The polarizat...We theoretically and numerically demonstrate that a transmission-type electrically tunable polarizer can be realized by using graphene ribbons supported on a dielectric film with a graphene sheet behind. The polarization mechanism originates from the antenna plasmon resonance of graphene stripes. The results of full-wave numerical simulations reveal that transmittance of 0.70 for one polarization and 0.0073 for another polarization can be obtained at normal incidence. The transmission-type electrically tunable polarizer provides and facilitates a variety of applications, including filtering, detecting, and imaging.展开更多
Coding metasurfaces make it possible to manipulate electromagnetic(EM)waves digitally by means of several discrete particles.Hence,there have been rapid advances in this field recently.Here we propose a novel design o...Coding metasurfaces make it possible to manipulate electromagnetic(EM)waves digitally by means of several discrete particles.Hence,there have been rapid advances in this field recently.Here we propose a novel design of a broadband transmission-type coding metasurface,which is valid to both x-and y-polarized EM incidences from 8.1-12.5 GHz while satisfies the requirements of 1-bit coding without changing the polarization.Two types of multi-layer coding particles with different geometrical parameters are adopted to represent the digital states"0"and"1",which are easily promoted to terahertz and optics through modifying the size scale.To verify the ability to manipulate the EM waves,we first adopt the coding metasurface to achieve broadband beam forming by converting spherical waves to plane waves and realize high-directivity pencil beam in far field with low side lobes.We further arrange the particles according to the coding sequence 010101…to steer two symmetrical beams in different directions controlled by frequencies with the maximum range of the scanning angle of 30°-50.5°.The good agreements between the simulated and measured results validate the proposed broadband coding metasurface,indicating its huge potential in communication and radar imaging systems.展开更多
Aiming at the all-weather automatic monitoring of bridge structure health monitoring,an embedded bridge multi-dimensional(horizontal and vertical)deflection monitoring system based on dual laser references is proposed...Aiming at the all-weather automatic monitoring of bridge structure health monitoring,an embedded bridge multi-dimensional(horizontal and vertical)deflection monitoring system based on dual laser references is proposed.The controller turns on the laser reference transmitter through instructions to emit the laser reference.The intelligent target system located in the middle of the span will calculate the multi-dimensional deflection and deformation information of the bridge structure according to the laser spot projected on the diffuse optical target,and pass this information through the wireless network communication unit transmits to the cloud platform to realize real-time monitoring of the bridge structure status and other parameters.Through the laboratory platform,it is found that the measurement error of this method is less than 300μm,and the data update rate is less than 66 ms,which meets the requirements of bridge structural health monitoring.This method solves the problem of low efficiency of artificial bridge deflection monitoring,realizes all-weather online real-time monitoring of bridge deflection detection,and ensures the accuracy and efficiency of the measurement system.Applying this monitoring technology not only significantly improves the efficiency and accuracy of bridge structural health monitoring but also plays a crucial role in ensuring safe bridge operations,extending the service life of bridges,and reducing maintenance costs.展开更多
The characteristics of transmission spectra for the all fiber, multi-cavity Fabry- Perot （FP） configuration based on fiber Bragg gratings （FBG） are theoretically analyzed and modeled. The general transmission matr...The characteristics of transmission spectra for the all fiber, multi-cavity Fabry- Perot （FP） configuration based on fiber Bragg gratings （FBG） are theoretically analyzed and modeled. The general transmission matrix function for the structure with any number of cavities is derived, and explicit expression of the power trans- mission coefficient for symmetrical two-cavity FP is presented. The general condi- tions for flat-top single resonant peak at the central wavelength in FBG stop band are derived and verified in the numerical simulation section. The transmission peaks of single-cavity and two-cavity FP structures are compared and discussed, and results show that compared to the single-cavity FP, flatness of the top and steepness at the edge of transmission peak can be improved by introducing one more cavity. The resonant transmission peak properties of two-cavity structure are investigated in detail for various values of cavity length and FBGs with different reflection characteristics, and the design guidelines for transmission-type filters are presented. The results show that the steepness of peak slope can be improved by increase of FBG reflectivities, and these kinds of filters can be used as nar- row-band single-channel selectors and multi-channel wavelength de-multiplexing by properly choosing the length of cavities and reflectivities of FBGs.展开更多
基金Supported by the National Basic Research Program of China under Grant No 2012CB933501the National Natural Science Foundation of China under Grant Nos 61177051,11304389,61404174 and 61205087
文摘We theoretically and numerically demonstrate that a transmission-type electrically tunable polarizer can be realized by using graphene ribbons supported on a dielectric film with a graphene sheet behind. The polarization mechanism originates from the antenna plasmon resonance of graphene stripes. The results of full-wave numerical simulations reveal that transmittance of 0.70 for one polarization and 0.0073 for another polarization can be obtained at normal incidence. The transmission-type electrically tunable polarizer provides and facilitates a variety of applications, including filtering, detecting, and imaging.
基金supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0700201,2017YFA0700202,and 2017YFA0700203)the National Natural Science Foundation of China(Grant Nos.61631007,61731010,61735010,61722106,61701107,and 61701108)+4 种基金the Fund for International Cooperation and Exchange of the National Natural Science Foundation of China(Grant No.61761136007)the Overseas Expertise Introduction Project for Discipline Innovation(Grant No.111-2-05)the Fundamental Research Funds for the Central UniversitiesPostgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX17_0092)the Scientific Research Foundation of Graduate School of Southeast University(Grant No.YBJJ1815)。
文摘Coding metasurfaces make it possible to manipulate electromagnetic(EM)waves digitally by means of several discrete particles.Hence,there have been rapid advances in this field recently.Here we propose a novel design of a broadband transmission-type coding metasurface,which is valid to both x-and y-polarized EM incidences from 8.1-12.5 GHz while satisfies the requirements of 1-bit coding without changing the polarization.Two types of multi-layer coding particles with different geometrical parameters are adopted to represent the digital states"0"and"1",which are easily promoted to terahertz and optics through modifying the size scale.To verify the ability to manipulate the EM waves,we first adopt the coding metasurface to achieve broadband beam forming by converting spherical waves to plane waves and realize high-directivity pencil beam in far field with low side lobes.We further arrange the particles according to the coding sequence 010101…to steer two symmetrical beams in different directions controlled by frequencies with the maximum range of the scanning angle of 30°-50.5°.The good agreements between the simulated and measured results validate the proposed broadband coding metasurface,indicating its huge potential in communication and radar imaging systems.
基金supported by National Natural Science Foundation of China(NSFC)(No.52172324)Shaanxi Provincial Key Research and Development Program(No.2021GY-285 and 2021SF-483)+1 种基金The Science and Technology Project of Shaanxi Provincial Transportation Department(No.21-20K)open fund project of the Xi'an Key Laboratory of Intelligent Expressway Information Fusion and Control(Chang'an University)(300102321502)。
文摘Aiming at the all-weather automatic monitoring of bridge structure health monitoring,an embedded bridge multi-dimensional(horizontal and vertical)deflection monitoring system based on dual laser references is proposed.The controller turns on the laser reference transmitter through instructions to emit the laser reference.The intelligent target system located in the middle of the span will calculate the multi-dimensional deflection and deformation information of the bridge structure according to the laser spot projected on the diffuse optical target,and pass this information through the wireless network communication unit transmits to the cloud platform to realize real-time monitoring of the bridge structure status and other parameters.Through the laboratory platform,it is found that the measurement error of this method is less than 300μm,and the data update rate is less than 66 ms,which meets the requirements of bridge structural health monitoring.This method solves the problem of low efficiency of artificial bridge deflection monitoring,realizes all-weather online real-time monitoring of bridge deflection detection,and ensures the accuracy and efficiency of the measurement system.Applying this monitoring technology not only significantly improves the efficiency and accuracy of bridge structural health monitoring but also plays a crucial role in ensuring safe bridge operations,extending the service life of bridges,and reducing maintenance costs.
基金Supported by the Fund of Beijing Jiaotong University (Grant No. 2006XZ010)the Program for New Century Excellent Telants in University (Grant No. NCET-06-0076)
文摘The characteristics of transmission spectra for the all fiber, multi-cavity Fabry- Perot （FP） configuration based on fiber Bragg gratings （FBG） are theoretically analyzed and modeled. The general transmission matrix function for the structure with any number of cavities is derived, and explicit expression of the power trans- mission coefficient for symmetrical two-cavity FP is presented. The general condi- tions for flat-top single resonant peak at the central wavelength in FBG stop band are derived and verified in the numerical simulation section. The transmission peaks of single-cavity and two-cavity FP structures are compared and discussed, and results show that compared to the single-cavity FP, flatness of the top and steepness at the edge of transmission peak can be improved by introducing one more cavity. The resonant transmission peak properties of two-cavity structure are investigated in detail for various values of cavity length and FBGs with different reflection characteristics, and the design guidelines for transmission-type filters are presented. The results show that the steepness of peak slope can be improved by increase of FBG reflectivities, and these kinds of filters can be used as nar- row-band single-channel selectors and multi-channel wavelength de-multiplexing by properly choosing the length of cavities and reflectivities of FBGs.
