A single baffle metal–insulator–metal(MIM)waveguide coupled with a semi-circular cavity and a cross-shaped cavity is proposed based on the multiple Fano resonance characteristics of surface plasmon polaritons(SPPs)s...A single baffle metal–insulator–metal(MIM)waveguide coupled with a semi-circular cavity and a cross-shaped cavity is proposed based on the multiple Fano resonance characteristics of surface plasmon polaritons(SPPs)subwavelength structure.The isolated state formed by two resonators interferes with the wider continuous state mode formed by the metal baffle,forming Fano resonance that can independently be tuned into five different modes.The formation mechanism of Fano resonance is analyzed based on the multimode interference coupled mode theory(MICMT).The finite element method(FEM)and MICMT are used to simulate the transmission spectra of this structure and analyze the influence of structural parameters on the refractive index sensing characteristics.And the transmission responses calculated by the FEM simulation are consistent with the MICMT theoretical results very well.The results show that the figure of merit(FOM)can reach 193 and the ultra-high sensitivity is 1600 nm/RIU after the structure parameters have been optimized,and can provide theoretical basis for designing the high sensitive refractive index sensors based on SPPs waveguide for high-density photonic integration with excellent performance in the near future.展开更多
This paper presents the theoretical investigation of hierarchical sub-wavelength photonic structures with various periods and numbers of layers, which were fabricated using a high-order waveguide-mode interference fie...This paper presents the theoretical investigation of hierarchical sub-wavelength photonic structures with various periods and numbers of layers, which were fabricated using a high-order waveguide-mode interference field. A 442-nm laser was used to excite high-order waveguide modes in an asymmetric metal-cladding dielectric waveguide structure. The dispersion curve of the waveguide modes was theoretically analyzed, and the distribution of the interference field of high-order waveguide modes was numerically simulated using the finite-element method. The various dependences of the characteristics of hierarchical sub-wavelength photonic structures on the thickness and refractive index of the photoresist and the waveguide mode were investigated in detail. These hierarchical sub-wavelength photonic structures have various periods and numbers of layers and can be fabricated by a simple and low-cost method.展开更多
The dispersion characteristics of a class of closed dielectric waveguides are investigated by themethod which combines the building-block approach of multimode network theory with the rigorous modematching procedure.S...The dispersion characteristics of a class of closed dielectric waveguides are investigated by themethod which combines the building-block approach of multimode network theory with the rigorous modematching procedure.Several numerical examples for difrerent guiding structures have been given by the ap-proach.The same structures are also analyzed with the finite element method and the EDC method forcomparison.The calculations show that the present approach yields as highly accurate results as the finite ele-ment method while almost retaining the simplicity of the EDC method,and justify the utility of the presentmethod.展开更多
In earlier approach, the 2-D acoustical field profiles on the substrate region are often calculated with BPM. In this paper, we present a new approach based on the finite element -artificial transmitting boundary meth...In earlier approach, the 2-D acoustical field profiles on the substrate region are often calculated with BPM. In this paper, we present a new approach based on the finite element -artificial transmitting boundary method and calculate acoustical field on the substrate region.展开更多
Eigenvalues of the dielectric-filled waveguide are of great importance to its transmission characteristic analysis and optimization design, which could be easily affected by spatially uncertain dielectric parameters. ...Eigenvalues of the dielectric-filled waveguide are of great importance to its transmission characteristic analysis and optimization design, which could be easily affected by spatially uncertain dielectric parameters. For the sake of quantifying their influence on eigenvalues of the dielectric-filled waveguide and overcoming the limitation of less samples, an interval vector finite element method(IVFEM) is proposed to acquire the lower and upper bounds of the eigenvalues with spatial uncertainty of the medium parameters. Firstly, the uncertain dielectric material properties are described by the interval field model and the corresponding interval Karhunen-Loève(K-L) approximate method. Secondly, by inserting the interval uncertainties into the constitutive relationship of the standard generalized eigenvalue equations of the dielectric-filled waveguide, an interval standard generalized eigenvalue equation is then formulated. At last, the lower and upper bounds of the eigenvalues are calculated according to the first-order perturbation method, which can be used to estimate the transmission properties of the waveguide efficiently. Three kinds of the dielectric-filled waveguides are analyzed by the proposed IVFEM and verified by Monte Carlo simulation method.展开更多
This paper concerns the reconstruction of a penetrable obstacle embedded in a waveg- uide using the scattered data due to point sources, which is formulated as an optimization problem. We propose a fast reconstruction...This paper concerns the reconstruction of a penetrable obstacle embedded in a waveg- uide using the scattered data due to point sources, which is formulated as an optimization problem. We propose a fast reconstruction method based on a carefully designed finite element scheme for the direct scattering problem. The method has several merits： 1） the linear sampling method is used to quickly obtain a good initial guess; 2） finite Fourier series are used to approximate the boundary of the obstacle, which is decoupled from the boundary used by the finite element method; and 3） the mesh is fixed and hence the stiff- ness matrix, mass matrix, and right hand side are assembled once and only minor changes are made at each iteration. The effectiveness of the proposed method is demonstrated by numerical examples.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National Natural Science Foundation of China(Grant Nos.61367005 and 61865008)the Natural Science Foundation of Gansu Province,China(Grant No.17JR5RA078).
文摘A single baffle metal–insulator–metal(MIM)waveguide coupled with a semi-circular cavity and a cross-shaped cavity is proposed based on the multiple Fano resonance characteristics of surface plasmon polaritons(SPPs)subwavelength structure.The isolated state formed by two resonators interferes with the wider continuous state mode formed by the metal baffle,forming Fano resonance that can independently be tuned into five different modes.The formation mechanism of Fano resonance is analyzed based on the multimode interference coupled mode theory(MICMT).The finite element method(FEM)and MICMT are used to simulate the transmission spectra of this structure and analyze the influence of structural parameters on the refractive index sensing characteristics.And the transmission responses calculated by the FEM simulation are consistent with the MICMT theoretical results very well.The results show that the figure of merit(FOM)can reach 193 and the ultra-high sensitivity is 1600 nm/RIU after the structure parameters have been optimized,and can provide theoretical basis for designing the high sensitive refractive index sensors based on SPPs waveguide for high-density photonic integration with excellent performance in the near future.
基金Project supported by the National Natural Science Foundation of China(Grant No.61505074)the National Key Basic Research Program of China(Grant No.2013CBA01703)the Hong Liu Young Teachers Training Program Funded Projects of Lanzhou University of Technology(Grant No.Q201509)
文摘This paper presents the theoretical investigation of hierarchical sub-wavelength photonic structures with various periods and numbers of layers, which were fabricated using a high-order waveguide-mode interference field. A 442-nm laser was used to excite high-order waveguide modes in an asymmetric metal-cladding dielectric waveguide structure. The dispersion curve of the waveguide modes was theoretically analyzed, and the distribution of the interference field of high-order waveguide modes was numerically simulated using the finite-element method. The various dependences of the characteristics of hierarchical sub-wavelength photonic structures on the thickness and refractive index of the photoresist and the waveguide mode were investigated in detail. These hierarchical sub-wavelength photonic structures have various periods and numbers of layers and can be fabricated by a simple and low-cost method.
基金Supported by the National Nature Seience Foundation of China
文摘The dispersion characteristics of a class of closed dielectric waveguides are investigated by themethod which combines the building-block approach of multimode network theory with the rigorous modematching procedure.Several numerical examples for difrerent guiding structures have been given by the ap-proach.The same structures are also analyzed with the finite element method and the EDC method forcomparison.The calculations show that the present approach yields as highly accurate results as the finite ele-ment method while almost retaining the simplicity of the EDC method,and justify the utility of the presentmethod.
基金This work was supported by the National Natural Science Fund of China (10084001) the Action Plan for Booming Education of Tianjin University.
文摘In earlier approach, the 2-D acoustical field profiles on the substrate region are often calculated with BPM. In this paper, we present a new approach based on the finite element -artificial transmitting boundary method and calculate acoustical field on the substrate region.
基金supported by the National Science Fund for Distinguished Young Scholars(Grant No.51725502)the National Natural Science Foundation of China(Grant No.11802089)the National Defense Fundamental Research Foundation of China(Grant No.JCKY2020110C105)。
文摘Eigenvalues of the dielectric-filled waveguide are of great importance to its transmission characteristic analysis and optimization design, which could be easily affected by spatially uncertain dielectric parameters. For the sake of quantifying their influence on eigenvalues of the dielectric-filled waveguide and overcoming the limitation of less samples, an interval vector finite element method(IVFEM) is proposed to acquire the lower and upper bounds of the eigenvalues with spatial uncertainty of the medium parameters. Firstly, the uncertain dielectric material properties are described by the interval field model and the corresponding interval Karhunen-Loève(K-L) approximate method. Secondly, by inserting the interval uncertainties into the constitutive relationship of the standard generalized eigenvalue equations of the dielectric-filled waveguide, an interval standard generalized eigenvalue equation is then formulated. At last, the lower and upper bounds of the eigenvalues are calculated according to the first-order perturbation method, which can be used to estimate the transmission properties of the waveguide efficiently. Three kinds of the dielectric-filled waveguides are analyzed by the proposed IVFEM and verified by Monte Carlo simulation method.
文摘This paper concerns the reconstruction of a penetrable obstacle embedded in a waveg- uide using the scattered data due to point sources, which is formulated as an optimization problem. We propose a fast reconstruction method based on a carefully designed finite element scheme for the direct scattering problem. The method has several merits： 1） the linear sampling method is used to quickly obtain a good initial guess; 2） finite Fourier series are used to approximate the boundary of the obstacle, which is decoupled from the boundary used by the finite element method; and 3） the mesh is fixed and hence the stiff- ness matrix, mass matrix, and right hand side are assembled once and only minor changes are made at each iteration. The effectiveness of the proposed method is demonstrated by numerical examples.
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。
