Spatiotemporal optical vortices(STOVs)exhibit characteristics of transverse orbital angular momentum(OAM)that is perpendicular to the direction of pulse propagation,indicating significant potential for diverse applica...Spatiotemporal optical vortices(STOVs)exhibit characteristics of transverse orbital angular momentum(OAM)that is perpendicular to the direction of pulse propagation,indicating significant potential for diverse applications.In this study,we employ vanadium dioxide and photonic crystal plates to design tunable transreflective dual-channel terahertz(THz)spatiotemporal vortex generation devices that possess multipolarization adaptability.In the reflection channel,we achieve active tunability of the topological dark lines by utilizing circularly polarized light,based on the topological dark phenomenon,and observe variations in the number of singularities across the parameter space from different observational perspectives.In the transmission channel,we generate independent vortex singularities using linearly polarized light.This multifunctional terahertz device offers a novel approach for the generation and active tuning of spatiotemporal vortices.展开更多
With the rapid advancement of terahertz technology,multif-unctional coding metasurfaces have emerged as a significant research frontier in this domain.However,the rigid geometric structure of traditional metasurfaces ...With the rapid advancement of terahertz technology,multif-unctional coding metasurfaces have emerged as a significant research frontier in this domain.However,the rigid geometric structure of traditional metasurfaces poses challenges in accommodating both multifunctionality and dynamic control requirements.This study proposes an adjustable exceptional topological phase coding metasurface device based on a Dirac semimetal(DSM).By optimizing the structural parameters to excite multiple exceptional points(EPs),the resulting topological phase distribution enables multi-dimensional control of terahertz waves.The results demonstrate that,under the incidence of left-handed circularly polarized(LCP)light,the metasurface device can stably generate vortex light with a topological charge of l=1.In the left-and right-handed circularly polarized channels,the wavefronts of the vortex beam and the split beam are independently controlled,enabling dual-channel digital holographic imaging of the numerals'0'and'5'.Near-field grayscale imaging of the little grey dog'pattern is achieved by exploiting the differentiated absorption characteristics of the EP under LCP illumination.Furthermore,by dynamically tuning the Fermi level of the DSM,reversible switching of the reflection mode state is realized under the same incident conditions.This research provides a theoretical and practical foundation for enhancing the capacity of terahertz communication systems and optimizing terahertz near-field and far-field imaging technologies.It also holds significant scientific value and application potential for advancing the development of independently adj ustable multifunctional devices.展开更多
基金National Natural Science Foundation of China(62375158,62105187)Natural Science Foundation of Shandong Province(ZR2021QF010,ZR2020MF107)Development Plan of Youth Innovation Team in Colleges and Universities of Shandong Province(2022KJ216)。
文摘Spatiotemporal optical vortices(STOVs)exhibit characteristics of transverse orbital angular momentum(OAM)that is perpendicular to the direction of pulse propagation,indicating significant potential for diverse applications.In this study,we employ vanadium dioxide and photonic crystal plates to design tunable transreflective dual-channel terahertz(THz)spatiotemporal vortex generation devices that possess multipolarization adaptability.In the reflection channel,we achieve active tunability of the topological dark lines by utilizing circularly polarized light,based on the topological dark phenomenon,and observe variations in the number of singularities across the parameter space from different observational perspectives.In the transmission channel,we generate independent vortex singularities using linearly polarized light.This multifunctional terahertz device offers a novel approach for the generation and active tuning of spatiotemporal vortices.
基金supported by the National Natural Science Foundation of China(Grant No.62375158)the Qingdao Natural Science Foundation(Grant No.25-1-1-153-zyydjch)the Development Plan of Youth Innovation Team in Colleges and Universities of Shandong Province(Grant No.2022KJ216)。
文摘With the rapid advancement of terahertz technology,multif-unctional coding metasurfaces have emerged as a significant research frontier in this domain.However,the rigid geometric structure of traditional metasurfaces poses challenges in accommodating both multifunctionality and dynamic control requirements.This study proposes an adjustable exceptional topological phase coding metasurface device based on a Dirac semimetal(DSM).By optimizing the structural parameters to excite multiple exceptional points(EPs),the resulting topological phase distribution enables multi-dimensional control of terahertz waves.The results demonstrate that,under the incidence of left-handed circularly polarized(LCP)light,the metasurface device can stably generate vortex light with a topological charge of l=1.In the left-and right-handed circularly polarized channels,the wavefronts of the vortex beam and the split beam are independently controlled,enabling dual-channel digital holographic imaging of the numerals'0'and'5'.Near-field grayscale imaging of the little grey dog'pattern is achieved by exploiting the differentiated absorption characteristics of the EP under LCP illumination.Furthermore,by dynamically tuning the Fermi level of the DSM,reversible switching of the reflection mode state is realized under the same incident conditions.This research provides a theoretical and practical foundation for enhancing the capacity of terahertz communication systems and optimizing terahertz near-field and far-field imaging technologies.It also holds significant scientific value and application potential for advancing the development of independently adj ustable multifunctional devices.
