The unique wave-manipulation capabilities of zero-index metamaterials(ZIMs)offer a new opportunity for realizing bound states in the continuum(BICs).However,the relationship between anomalous scattering and BICs remai...The unique wave-manipulation capabilities of zero-index metamaterials(ZIMs)offer a new opportunity for realizing bound states in the continuum(BICs).However,the relationship between anomalous scattering and BICs remains underexplored when parity–time(PT)symmetry is introduced.In this work,we demonstrate that a BIC splits into a pair of lasing modes carrying opposite topological charges by introducing PT symmetry through gain-loss cylinders embedded in ZIM layers.Theoretical analysis and numerical simulations reveal that lasing and unidirectional transparency phenomena result from the singularities and exceptional points of the scattering matrix.Moreover,exceptional points can be tuned via propagation phase modulation in the air gap,and their coalescence produces quasi-BICs with symmetric responses.This work provides a framework for manipulating BICs and topological lasing modes in non-Hermitian systems,offering new insights for designing non-Hermitian photonic devices.展开更多
We investigate a one-dimensional acoustic metamaterial with a refractive index of near zero（RINZ） using an array of very thin elastic membranes located along a narrow waveguide pipe. The characteristics of the effec...We investigate a one-dimensional acoustic metamaterial with a refractive index of near zero（RINZ） using an array of very thin elastic membranes located along a narrow waveguide pipe. The characteristics of the effective density, refractive index, and phase velocity of the metamaterial indicate that, at the resonant frequency fm, the metamaterial has zero mass density and a phase transmission that is nearly uniform. We present a mechanism for dramatic acoustic energy squeezing and anomalous acoustic transmission by connecting the metamaterial to a normal waveguide with a larger cross-section. It is shown that at a specific frequency f1, transmission enhancement and energy squeezing are achieved despite the strong geometrical mismatch between the metamaterial and the normal waveguide. Moreover, to confirm the energy transfer properties, the acoustic pressure distribution, acoustic wave reflection coefficient, and energy transmission coefficient are also calculated. These results prove that the RINZ metamaterial provides a new design method for acoustic energy squeezing,super coupling, wave front transformation, and acoustic wave filtering.展开更多
A simple three-level system is proposed to produce high index of refraction with zero absorption in an Er^3＋-doped yttrium aluminium garnet （YAG） crystal, which is achieved for a probe field between the excited sta...A simple three-level system is proposed to produce high index of refraction with zero absorption in an Er^3＋-doped yttrium aluminium garnet （YAG） crystal, which is achieved for a probe field between the excited state 4I13/2 and ground state 4I15/2 by adjusting a strong coherent driving field between the upper excited state 4I11/2 and 4I15/2. It is found that the changes of the frequency of the coherent driving field and the concentration of Er^3＋ ions in the YAG crystal can maximize the index of refraction accompanied by vanishing absorption. This result could be useful for the dispersion compensation in fibre communication, laser particle acceleration, high precision magnetometry and so on.展开更多
目的近零折射率(index near zero,INZ)模式在光通信和物理诊疗等领域展现出巨大应用潜力,但其调制通常依赖复杂的实验手段,这限制了其更广泛的应用。因此,设计并验证灵活可调的INZ模式及其应用场景在当下尤为重要。方法本研究提出两种...目的近零折射率(index near zero,INZ)模式在光通信和物理诊疗等领域展现出巨大应用潜力,但其调制通常依赖复杂的实验手段,这限制了其更广泛的应用。因此,设计并验证灵活可调的INZ模式及其应用场景在当下尤为重要。方法本研究提出两种基于钇铁石榴石(yttrium iron garnet,YIG)的亚波长磁光单向波导,通过理论分析波导结构中表面模式的色散曲线与波导参数的关系,明确调控INZ模式的理论并通过有限元法等技术验证理论结果。结果研究发现了新颖的宽带可调谐INZ模式。这些模式的频率明确依赖于外部磁场,具有可预测且精确可调的特性。基于此,本团队通过简单调控外部磁场,设计了宽带可调谐全光相位调控器及一种慢波INZ装置,并创新性地提出了一种基于可调控INZ模式的微波热疗理论。结论本团队设计的单向波导中的INZ模式具有可调控性和宽带的特性,利用单向INZ模式实现的功能器件为小型化全光通信和计算提供了新的可能性,也可用于如非介入式可控微波热疗等医疗领域。展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12504361,12274313,and 62465005)the Natural Science Foundation of Guangxi(Grant No.2025GXNSFBA069179)the Guangxi Colleges and Universities Young and Middle-aged Teachers’Basic Scientific Research Ability Enhancement Project(Grant No.2025KY0093)。
文摘The unique wave-manipulation capabilities of zero-index metamaterials(ZIMs)offer a new opportunity for realizing bound states in the continuum(BICs).However,the relationship between anomalous scattering and BICs remains underexplored when parity–time(PT)symmetry is introduced.In this work,we demonstrate that a BIC splits into a pair of lasing modes carrying opposite topological charges by introducing PT symmetry through gain-loss cylinders embedded in ZIM layers.Theoretical analysis and numerical simulations reveal that lasing and unidirectional transparency phenomena result from the singularities and exceptional points of the scattering matrix.Moreover,exceptional points can be tuned via propagation phase modulation in the air gap,and their coalescence produces quasi-BICs with symmetric responses.This work provides a framework for manipulating BICs and topological lasing modes in non-Hermitian systems,offering new insights for designing non-Hermitian photonic devices.
基金supported by the National Natural Science Foundation of China(Grant Nos.61571222,11104142,and 11474160)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20161009)+1 种基金the Qing Lan Project of Jiangsu Province,Chinathe Six Talent Peaks Project of Jiangsu Province,China
文摘We investigate a one-dimensional acoustic metamaterial with a refractive index of near zero（RINZ） using an array of very thin elastic membranes located along a narrow waveguide pipe. The characteristics of the effective density, refractive index, and phase velocity of the metamaterial indicate that, at the resonant frequency fm, the metamaterial has zero mass density and a phase transmission that is nearly uniform. We present a mechanism for dramatic acoustic energy squeezing and anomalous acoustic transmission by connecting the metamaterial to a normal waveguide with a larger cross-section. It is shown that at a specific frequency f1, transmission enhancement and energy squeezing are achieved despite the strong geometrical mismatch between the metamaterial and the normal waveguide. Moreover, to confirm the energy transfer properties, the acoustic pressure distribution, acoustic wave reflection coefficient, and energy transmission coefficient are also calculated. These results prove that the RINZ metamaterial provides a new design method for acoustic energy squeezing,super coupling, wave front transformation, and acoustic wave filtering.
基金Project supported by the National Natural Science Foundation of China （Grant No 10334010）.
文摘A simple three-level system is proposed to produce high index of refraction with zero absorption in an Er^3＋-doped yttrium aluminium garnet （YAG） crystal, which is achieved for a probe field between the excited state 4I13/2 and ground state 4I15/2 by adjusting a strong coherent driving field between the upper excited state 4I11/2 and 4I15/2. It is found that the changes of the frequency of the coherent driving field and the concentration of Er^3＋ ions in the YAG crystal can maximize the index of refraction accompanied by vanishing absorption. This result could be useful for the dispersion compensation in fibre communication, laser particle acceleration, high precision magnetometry and so on.
文摘目的近零折射率(index near zero,INZ)模式在光通信和物理诊疗等领域展现出巨大应用潜力,但其调制通常依赖复杂的实验手段,这限制了其更广泛的应用。因此,设计并验证灵活可调的INZ模式及其应用场景在当下尤为重要。方法本研究提出两种基于钇铁石榴石(yttrium iron garnet,YIG)的亚波长磁光单向波导,通过理论分析波导结构中表面模式的色散曲线与波导参数的关系,明确调控INZ模式的理论并通过有限元法等技术验证理论结果。结果研究发现了新颖的宽带可调谐INZ模式。这些模式的频率明确依赖于外部磁场,具有可预测且精确可调的特性。基于此,本团队通过简单调控外部磁场,设计了宽带可调谐全光相位调控器及一种慢波INZ装置,并创新性地提出了一种基于可调控INZ模式的微波热疗理论。结论本团队设计的单向波导中的INZ模式具有可调控性和宽带的特性,利用单向INZ模式实现的功能器件为小型化全光通信和计算提供了新的可能性,也可用于如非介入式可控微波热疗等医疗领域。
