Off-axis-rotating elliptical Gaussian beams(Oare GB)oblique incidence in strong nonlocal medium exhibit novel propagation properties.The analytical expressions of semi-axial beam widths,and center-of-mass trajectory e...Off-axis-rotating elliptical Gaussian beams(Oare GB)oblique incidence in strong nonlocal medium exhibit novel propagation properties.The analytical expressions of semi-axial beam widths,and center-of-mass trajectory equations for transmitting off-axis-rotating elliptical Gaussian beams in strong nonlocal media are obtained using the ABCD transfer matrix method.The study revealed that the trajectory of the mass's center in the cross-section can be controlled by changing the sizes of the Oare GB parameters c,d,ζ,and f.The gradient force of the light field causes the spot region to form a spatial potential well in the media,and this spatial potential well can effectively capture nanoparticles.The particles captured by the light field can move along with the beam,realizing the effective manipulation of the particle trajectory.These laws may be applied to modulating the propagation path of light beams and optical tweezer technology.展开更多
Plasmonic vortices confining orbital angular momentums to surface have aroused wide research interest in the last decade.Recent advances of near-field microscopes have enabled the study on the spatiotemporal dynamics ...Plasmonic vortices confining orbital angular momentums to surface have aroused wide research interest in the last decade.Recent advances of near-field microscopes have enabled the study on the spatiotemporal dynamics of plasmonic vortices,providing a better understanding of optical orbital angular momentums in the evanescent wave regime.However,these works only focused on the objective characterization of plasmonic vortex and have not achieved subjectively tailoring of its spatiotemporal dynamics for specific applications.Herein,it is demonstrated that the plasmonic vortices with the same topological charge can be endowed with distinct spatiotemporal dynamics by simply changing the coupler design.Based on a near-field scanning terahertz microscopy,the surface plasmon fields are directly obtained with ultrahigh spatiotemporal resolution,experimentally exhibiting the generation and evolution divergences during the whole lifetime of plasmonic vortices.The proposed strategy is straightforward and universal,which can be readily applied into visible or infrared frequencies,facilitating the development of plasmonic vortex related researches and applications.展开更多
The asymmetric transmission(AT) and polarization conversion of terahertz(THz) wave play a vital role in future THz communication,spectrum,and information processing.Generally,it is very difficult and complicated to ac...The asymmetric transmission(AT) and polarization conversion of terahertz(THz) wave play a vital role in future THz communication,spectrum,and information processing.Generally,it is very difficult and complicated to actively control the AT of electromagnetic(EM) wave by using traditional devices.Here,we theoretically demonstrate a stereo-metamaterial(stereo-MM) consisting of a layer of metal structure and a layer of phase transition structure with a polyimide spacer in between.The performance of the device is simulated by using the finite-integration-technology(FIT).The results show that the AT and polarization conversion of linearly polarized wave can be dynamically controlled in a range of 1.0 THz-1.6 THz when the conductivity c,F of vanadium dioxide(VO2) is changed under the external stimulation.This study provides an example of actively controlling of the AT and polarization conversion of the EM wave.展开更多
We experimentally demonstrate an electrically triggered terahertz(THz) dual-band tunable band-pass filter based on Si_3 N_4–VO_2–Si_3 N_4 sandwich-structured hybrid metamaterials. The insulator–metal phase transiti...We experimentally demonstrate an electrically triggered terahertz(THz) dual-band tunable band-pass filter based on Si_3 N_4–VO_2–Si_3 N_4 sandwich-structured hybrid metamaterials. The insulator–metal phase transition of VO_2 film is induced by the Joule thermal effect of the top metal layer. The finite-integration-time-domain(FITD) method and finite element method(FEM) are used for numerical simulations. The sample is fabricated using a surface micromachining process,and characterized by a THz time-domain-spectrometer(TDS). When the bias current is 0.225 A, the intensity modulation depths at two central frequencies of 0.56 THz and 0.91 THz are about 81.7% and 81.3%, respectively. This novel design can achieve dynamically electric–thermo–optic modulation in the THz region, and has potential applications in the fields of THz communications, imaging, sensing, and astronomy exploration.展开更多
Bound states in the continuum(BICs)have exhibited extraordinary properties in photonics for enhanced light-matter interactions that enable appealing applications in nonlinear optics,biosensors,and ultrafast optical sw...Bound states in the continuum(BICs)have exhibited extraordinary properties in photonics for enhanced light-matter interactions that enable appealing applications in nonlinear optics,biosensors,and ultrafast optical switches.The most common strategy to apply BICs in a metasurface is by breaking symmetry of resonators in the uniform array that leaks the otherwise uncoupled mode to free space and exhibits an inverse quadratic relationship between quality factor(Q)and asymmetry.Here,we propose a scheme to further reduce scattering losses and improve the robustness of symmetry-protected BICs by decreasing the radiation density with a hybrid BIC lattice.We observe a significant increase of radiative Q in the hybrid lattice compared to the uniform lattice with a factor larger than 14.6.In the hybrid BIC lattice,modes are transferred toГpoint inherited from high symmetric X,Y,and M points in the Brillouin zone that reveal as multiple Fano resonances in the far field and would find applications in hyperspectral sensing.This work initiates a novel and generalized path toward reducing scattering losses and improving the robustness of BICs in terms of lattice engineering that would release the rigid requirements of fabrication accuracy and benefit applications of photonics and optoelectronic devices.展开更多
We numerically demonstrate a photo-excited plasmon-induced transparency(PIT)effect in hybrid terahertz(THz)metamaterials.The proposed metamaterials are regular arrays of hybrid unit cells composed of a metallic cut wi...We numerically demonstrate a photo-excited plasmon-induced transparency(PIT)effect in hybrid terahertz(THz)metamaterials.The proposed metamaterials are regular arrays of hybrid unit cells composed of a metallic cut wire and four metallic split-ring resonators(SRRs)whose gaps are filled with photosensitive semiconductor gallium arsenide(GaAs)patches.We simulate the PIT effect controlled by external infrared light intensity to change the conductivity of GaAs.In the absence of photo excitation,the conductivity of Ga As is 0,thus the SRR gaps are disconnected,and the PIT effect is not observed since the dark resonator(supported by the hybrid SRRs)cannot be stimulated.When the conductivity of GaAs is increased via photo excitation,the conductivity of Ga As can increase rapidly from 0 S/m to 1×10^(6)S/m and GaAs can connect the metal aluminum SRR gaps,and the dark resonator is excited through coupling with the bright resonator(supported by the cut wire),which leads to the PIT effect.Therefore,the PIT effect can be dynamically tuned between the on and off states by controlling the intensity of the external infrared light.We also discuss couplings between one bright mode(CW)and several dark modes(SRRs)with different sizes.The interference analytically described by the coupled Lorentz oscillator model elucidates the coupling mechanism between one bright mode and two dark modes.The phenomenon can be considered the result of linear superposition of the coupling between the bright mode and each dark mode.The proposed metamaterials are promising for application in the fields of THz communications,optical storage,optical display,and imaging.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.62075047)the Natural Science Foundation of Guangxi Zhuang Autonomous Region,China(Grant No.2020GXNSFDA297019)。
文摘Off-axis-rotating elliptical Gaussian beams(Oare GB)oblique incidence in strong nonlocal medium exhibit novel propagation properties.The analytical expressions of semi-axial beam widths,and center-of-mass trajectory equations for transmitting off-axis-rotating elliptical Gaussian beams in strong nonlocal media are obtained using the ABCD transfer matrix method.The study revealed that the trajectory of the mass's center in the cross-section can be controlled by changing the sizes of the Oare GB parameters c,d,ζ,and f.The gradient force of the light field causes the spot region to form a spatial potential well in the media,and this spatial potential well can effectively capture nanoparticles.The particles captured by the light field can move along with the beam,realizing the effective manipulation of the particle trajectory.These laws may be applied to modulating the propagation path of light beams and optical tweezer technology.
基金supported by the National Natural Science Foundation of China(62005193,62135008,62075158,62025504,61935015)the National Science Foundation(2114103)Guangxi Key Laboratory of Optoelectroric Information Processing(GD20202).
文摘Plasmonic vortices confining orbital angular momentums to surface have aroused wide research interest in the last decade.Recent advances of near-field microscopes have enabled the study on the spatiotemporal dynamics of plasmonic vortices,providing a better understanding of optical orbital angular momentums in the evanescent wave regime.However,these works only focused on the objective characterization of plasmonic vortex and have not achieved subjectively tailoring of its spatiotemporal dynamics for specific applications.Herein,it is demonstrated that the plasmonic vortices with the same topological charge can be endowed with distinct spatiotemporal dynamics by simply changing the coupler design.Based on a near-field scanning terahertz microscopy,the surface plasmon fields are directly obtained with ultrahigh spatiotemporal resolution,experimentally exhibiting the generation and evolution divergences during the whole lifetime of plasmonic vortices.The proposed strategy is straightforward and universal,which can be readily applied into visible or infrared frequencies,facilitating the development of plasmonic vortex related researches and applications.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574059 and 61965005)the National Technology Major Special Project,China(Grant No.2017ZX02101007-003)+2 种基金the Natural Science Foundation of Guangxi Zhuang Autonomous Region,China(Grant No.2018GXNSFAA050043)the Guangxi Special Expert Program and Innovation Project of Guangxi Graduate Education,China(Grant Nos.2019YCXS088 and 2019YCXS094)the Foundation from Guangxi Key Laboratory of Automatic Detection Technology and Instrument,China(Grant No.YQ16101).
文摘The asymmetric transmission(AT) and polarization conversion of terahertz(THz) wave play a vital role in future THz communication,spectrum,and information processing.Generally,it is very difficult and complicated to actively control the AT of electromagnetic(EM) wave by using traditional devices.Here,we theoretically demonstrate a stereo-metamaterial(stereo-MM) consisting of a layer of metal structure and a layer of phase transition structure with a polyimide spacer in between.The performance of the device is simulated by using the finite-integration-technology(FIT).The results show that the AT and polarization conversion of linearly polarized wave can be dynamically controlled in a range of 1.0 THz-1.6 THz when the conductivity c,F of vanadium dioxide(VO2) is changed under the external stimulation.This study provides an example of actively controlling of the AT and polarization conversion of the EM wave.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574059,61565004,and 11774288)the National Technology Major Special Project,China(Grant No.2017ZX02101007-003)+2 种基金the Natural Science Foundation of Guangxi,China(Grant Nos.2015GXNSFDA139039 and2017GXNSFBA198116)the Foundation from Guangxi Key Laboratory of Automatic Detection Technology and Instrument,China(Grant No.YQ16101)the Innovation of Guangxi Graduate Education,China(Grant Nos.2018YJCX70,2018YJCX67,and 2018YJCX74)
文摘We experimentally demonstrate an electrically triggered terahertz(THz) dual-band tunable band-pass filter based on Si_3 N_4–VO_2–Si_3 N_4 sandwich-structured hybrid metamaterials. The insulator–metal phase transition of VO_2 film is induced by the Joule thermal effect of the top metal layer. The finite-integration-time-domain(FITD) method and finite element method(FEM) are used for numerical simulations. The sample is fabricated using a surface micromachining process,and characterized by a THz time-domain-spectrometer(TDS). When the bias current is 0.225 A, the intensity modulation depths at two central frequencies of 0.56 THz and 0.91 THz are about 81.7% and 81.3%, respectively. This novel design can achieve dynamically electric–thermo–optic modulation in the THz region, and has potential applications in the fields of THz communications, imaging, sensing, and astronomy exploration.
基金This work was supported by the National Natural Science Foundation of China(Award No.62175099)Guangdong Basic and Applied Basic Research Foundation(Award No.2023A1515011085)+1 种基金Stable Support Program for Higher Education Institutions from Shenzhen Science,Technology&Innovation Commission(Award No.20220815151149004)Global recruitment program of young experts of China,and startup funding of Southern University of Science and Technology.The authors acknowledge the assistance of SUSTech Core Research Facilities and thank Yao Wang for helpful discussions on fabrication.
文摘Bound states in the continuum(BICs)have exhibited extraordinary properties in photonics for enhanced light-matter interactions that enable appealing applications in nonlinear optics,biosensors,and ultrafast optical switches.The most common strategy to apply BICs in a metasurface is by breaking symmetry of resonators in the uniform array that leaks the otherwise uncoupled mode to free space and exhibits an inverse quadratic relationship between quality factor(Q)and asymmetry.Here,we propose a scheme to further reduce scattering losses and improve the robustness of symmetry-protected BICs by decreasing the radiation density with a hybrid BIC lattice.We observe a significant increase of radiative Q in the hybrid lattice compared to the uniform lattice with a factor larger than 14.6.In the hybrid BIC lattice,modes are transferred toГpoint inherited from high symmetric X,Y,and M points in the Brillouin zone that reveal as multiple Fano resonances in the far field and would find applications in hyperspectral sensing.This work initiates a novel and generalized path toward reducing scattering losses and improving the robustness of BICs in terms of lattice engineering that would release the rigid requirements of fabrication accuracy and benefit applications of photonics and optoelectronic devices.
基金supported by the National Science and Technology Major Project(Grant No.2017ZX02101007-003)the National Natural Science Foundation of China(Grant No.61965005)+4 种基金the National Natural Science Foundation of China(Grant No.62105187)the Natural Science Foundation of Guangxi Province(Grant No.2019GXNSFDA185010)Guangxi Distinguished Expert Project,Foundation of Guangxi Key Laboratory of Optoelectronic Information Processing(Grant No.GD20104)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2021QF010)the Innovation Project of Guang Xi Graduate Education(Grant No.YCSW2020158)。
文摘We numerically demonstrate a photo-excited plasmon-induced transparency(PIT)effect in hybrid terahertz(THz)metamaterials.The proposed metamaterials are regular arrays of hybrid unit cells composed of a metallic cut wire and four metallic split-ring resonators(SRRs)whose gaps are filled with photosensitive semiconductor gallium arsenide(GaAs)patches.We simulate the PIT effect controlled by external infrared light intensity to change the conductivity of GaAs.In the absence of photo excitation,the conductivity of Ga As is 0,thus the SRR gaps are disconnected,and the PIT effect is not observed since the dark resonator(supported by the hybrid SRRs)cannot be stimulated.When the conductivity of GaAs is increased via photo excitation,the conductivity of Ga As can increase rapidly from 0 S/m to 1×10^(6)S/m and GaAs can connect the metal aluminum SRR gaps,and the dark resonator is excited through coupling with the bright resonator(supported by the cut wire),which leads to the PIT effect.Therefore,the PIT effect can be dynamically tuned between the on and off states by controlling the intensity of the external infrared light.We also discuss couplings between one bright mode(CW)and several dark modes(SRRs)with different sizes.The interference analytically described by the coupled Lorentz oscillator model elucidates the coupling mechanism between one bright mode and two dark modes.The phenomenon can be considered the result of linear superposition of the coupling between the bright mode and each dark mode.The proposed metamaterials are promising for application in the fields of THz communications,optical storage,optical display,and imaging.
