加载异向介质非辐射介质波导中的慢波传输及应用

将开口谐振环作为加载单元,分析了含有开口谐振环结构非辐射介质波导的新型传输特性.由于异向介质的双各向异性效应,纵剖面磁波型和纵剖面电波型在此新型非辐射介质波导中的传输速度能够减慢,甚至达到零速度.对于波导中的能量关系也进行了分析,研究表明,在一定情况下,慢波传输将引起功率流动的增强.这些特性使得此新型非辐射介质波导更能满足小型化的设计要求. 关键词： 开口谐振环 异向介质 非辐射介质波导 慢波传输     

含有异向介质H形波导的特性研究

将开口谐振环作为加载单元,分析了含有异向介质H形波导的新型传输特性.由于异向介质的双各向异性效应,纵剖面磁波型和纵剖面电波型在此新型导波结构中的相速度能够减慢,并且会引起功率流动的增强.在一些情况下,纵剖面磁波型和纵剖面电波型将出现传播常量随频率增高而减小的异常高次模式.而在其它情况下,利用双各向异性效应可以有效减少纵剖面磁和纵剖面电波型的高次模漏波现象.尤其当异向介质取得单负参量时,此新型导波结构将能够完全抑制高次模漏波的出现.     

含有异向介质H形波导的特性研究

将开口谐振环作为加载单元,分析了含有异向介质H形波导的新型传输特性.由于异向介质的双各向异性效应,纵剖面磁波型和纵剖面电波型在此新型导波结构中的相速度能够减慢,并且会引起功率流动的增强.在一些情况下,纵剖面磁波型和纵剖面电波型将出现传播常量随频率增高而减小的异常高次模式.而在其它情况下,利用双各向异性效应可以有效减少纵剖面磁和纵剖面电波型的高次模漏波现象.尤其当异向介质取得单负参量时,此新型导波结构将能够完全抑制高次模漏波的出现.     

单轴各向异性异向介质平板波导中的导模特性

 推导了介电常数张量和磁导率张量中各分量带有不同符号的单轴各向异性异向介质平板波导的导行条件。根据分量符号的正负组合,分情况讨论了导行TE波的偶模特性,画出了平板波导中为实横波数时的布里渊图。结果表明,在特定条件下此平板波导中有无穷多导模,这与传统介质波导及各向同性异向介质平板中只有有限数量模式存在有很大不同。此外,还发现当分量参数满足一定条件时,出现了多个虚横波数的传输模式解,并且该模式存在高频截止。     

各向异性非线性介质平板波导中的TM波

本文讨论了在三层平板介质波导中TM₀模的传播问题.三层介质的芯区是一层各向异性的Kerr型介质,上下两层则是线性介质.本文将利用E_x² >> E_x²这一性质,求解非线性方程组,给出零级近似和1级近似的解析解.     

填充等离子体的介质同轴波导中的切伦科夫辐射

 利用自洽线性场理论，导出了薄环形相对论电子注通过填充等离子体的介质同轴波导中的注波互作用色散方程，得到了注波互作用产生切伦科夫辐射的同步条件和波增长率。分析了填充等离子体后的波与电子注之间的能量交换及等离子体密度对色散特性、波增长率和注波能量交换的影响。分析结果表明：切伦科夫辐射是由沿介质同轴波导传播的慢波与沿薄环形相对论电子注传播的负能空间电荷波耦合所致，且其耦合强度与电子注的密度成正比；输出频率和波增长率随着填充等离子体密度的增大而提高；保持一定的输出频率，增大电子注的束流可得到高的微波输出功率。     

异向介质谐振响应的Floquet模分析

将开口谐振环单元的场分布利用Floquet模展开,从电磁波传播角度揭示了凋落模引起异向介质谐振响应的事实.数值计算了任意平面电磁波照射下异向介质的传输特性.研究表明,对于来自主平面上的垂直或平行极化的入射波,具有相同极化方式的Floquet透射模将发生谐振,并且磁谐振和电谐振将随着入射角的不同而改变.而对于来自其他入射平面的电磁波,两种极化的Floquet透射模将共同发生谐振. 关键词： 开口谐振环 异向介质 Floquet模 谐振     

双通带异向平板波导的特性

提出了一种基于平板波导的新型异向谐振结构——交叉椅型谐振结构,通过理论分析和数值计算,说明和验证了单个交叉椅型谐振结构加载的平板波导具有双通带特性和异向特性;设计了一种由多个交叉椅型谐振结构周期加载的异向平板波导结构,并通过仿真实验验证了其负折射特性。交叉椅型谐振结构的全金属半封闭式结构和其特殊的电磁谐振方式,使得此类2维异向平板波导与传统的由金属开口谐振环与金属线正交阵列而成的2维异向介质相比,具有双通带、无介质损耗、功率容量大等特异性质;单个交叉椅型谐振结构加载的平板波导作为一种新型的滤波器结构,具有良好的双通带特性,尺寸较小。     

双通带异向平板波导的特性

提出了一种基于平板波导的新型异向谐振结构——交叉椅型谐振结构,通过理论分析和数值计算,说明和验证了单个交叉椅型谐振结构加载的平板波导具有双通带特性和异向特性;设计了一种由多个交叉椅型谐振结构周期加载的异向平板波导结构,并通过仿真实验验证了其负折射特性。交叉椅型谐振结构的全金属半封闭式结构和其特殊的电磁谐振方式,使得此类2维异向平板波导与传统的由金属开口谐振环与金属线正交阵列而成的2维异向介质相比,具有双通带、无介质损耗、功率容量大等特异性质;单个交叉椅型谐振结构加载的平板波导作为一种新型的滤波器结构,具有良好的双通带特性,尺寸较小。     

四种非矩形截面传感波导中的TE波和TM波

用保角变换将非矩形截面传感波导变换成等效矩形截面波导．给出计算等效矩形截面波导的TE模和TM模、电磁场、临界频率、波导壁电流、功率传输和衰减的公式．并给出4种非矩形传感截面波导数值计算的例子．     

Electric and magnetic dipole couplings in split ring resonator metamaterials

In this paper, the electric and the magnetic dipole couplings between the outer and the inner rings of a single split ring resonator (SRR) are investigated. We numerically demonstrate that the magnetic resonance frequency can be substantially modified by changing the couplings of the electric and magnetic dipoles, and give a theoretical expression of the magnetic resonance frequency. The results in this work are expected to be conducive to a deeper understanding of the SRR and other similar metamaterials, and provide new guidance for complex metamaterials design with a tailored electromagnetic response.     

Screw split ring resonator as building block of three-dimensional chiral metamaterials

We proposed and numerically investigated the influence of spatial topology on the infrared frequency region response of chiral metamaterials based on discrete deformed split ring resonators. Compared with the well studied continuous helix, the proposed metamaterials with discrete topology exhibit broad band chiral electromagnetic response. It is shown that the conversion between left and right circular polarization waves for our model is much broader than the continuous helix model. The observed cross-coupling between electric and magnetic fields results from the chiral electric currents on the resonators due to the broken mirror symmetry. The findings are useful for the design of future real three-dimensional chiral metamaterials with tunable optical response.     

谐振频率可调的环状开口谐振器结构及其效应

理论和实验研究表明，开口谐振环(SRRs)中可以激励磁谐振从而实现负磁导率.通过在SRRs结构中引入与其开口边平行的金属短杆设计并制备了新的磁谐振单元，采用波导法系统研究了短杆对SRRs和左手材料的微波透射特性以及左手效应的影响.实验和数值模拟表明：金属短杆和SRRs开口边形成附加电容，导致SRRs开口电容增大从而引起谐振频率降低.随短杆长度l和短杆与SRRs间距d的增大，SRRs谐振频率也随之减小和增加.短杆的加入不影响SRRs的负磁导率特性，改变短杆与SRRs间距d< 关键词： 开口谐振环 金属短杆 调控 左手材料     

Magnetic response of split ring resonator metamaterials: From effective medium dispersion to photonic band gaps

On systematically investigating the electromagnetic response of periodic split-ring resonator (SRR) metamaterials as a function of the size-to-wavelength (a/λ) ratio, we find that the stop bands due to the geometric resonances of the SRR weaken with increasing (a/λ) ratio, and are eventually replaced by stop bands due to Bragg scattering. Our study traces the behaviour of SRR-based metamaterials as the resonance frequency increases and the wavelength of the radiation finally becomes comparable to the size of the unit cell of the metamaterial. In the intermediate stages, the dispersion of the SRR metamaterial can still be described as due to a localized magnetic resonances while Bragg scattering finally becomes the dominant phenomenon as a/λ∼1/2.     

A dual-band polarization insensitive metamaterial absorber with split ring resonator

A dual-band polarization insensitive absorber has been proposed . Unlike the previous dual band absorber composed of composite structures, only one square metal ring with a slit at the middle of each side can be used to achieve the dual-band absorption. The calculated results show two distinct absorption peaks of 0.96 at 10 GHz and 0.99 at 20 GHz. In addition, the positions of the two peaks are strongly influenced by the width of the slit (g). More importantly, the absorptions of the two peaks keep higher than 0.9 while g changing. The dual-band absorber may have many potential applications in scientific and technological areas because of its excellent absorption characteristics and concise structure.     

垂直入射条件下金属环的谐振特性

本文研究垂直入射条件下水平极化和垂直极化时金属开口谐振环(split ring resonator, SRR)的电磁响应行为. 通过分析这两种情况下的透射系数、介电常数和磁导率, 发现垂直极化时, SRR可以产生电谐振实现负介电常数, 其频段远高于磁谐振频段; 水平极化时, SRR只能产生磁谐振实现负磁导率, 其频段与水平入射时的SRR的磁谐振频段相对应. 通过仿真对此进行了证明, 并对产生电谐振和磁谐振的原因进行了分析.     

Strong Brillouin suppression in a passive fiber ring resonator

We demonstrate the passive suppression of stimulated Brillouin scattering in meter-length fiber-ring cavities through careful control of the fiber length. Experimentally we are able to demonstrate an over sixty-times increase in the Brillouin threshold of a 0.4 m fiber ring. This very simple suppression technique greatly simplifies the design of optical parametric devices based on fiber-ring cavities.     

含有凹口的金属纳米环形共振器的本征模式分裂

提出了一种含有凹口金属纳米环形共振器结构,采用时域有限差分方法模拟了表面等离子体在这种结构中的传播特性.详细研究了凹口的长度、位置以及环的半径对透射性质的影响,发现当凹口的长度满足一定条件,并且处于某些特定位置的时候,与没有凹口的环形共振器相比,本征透射模式会发生分裂.随着环半径的增加,透射模式会向长波长方向移动,但不会对模式的分裂造成影响.     

Systematic phase difference between opposing beam modes in an oscillating ring resonator

Journal of Applied Spectroscopy -     

Study on the resonance properties of combinations of different split ring resonator cells

We combine different split ring resonator (SRR) unit cells along three axes respectively and study the electromagnetic behaviors of combinations numerically, with the purpose of broadening the frequency band of negative permeability. When combining SRRs in z-direction, the wave propagation direction, it is found that the bandwidth of negative permeability is broadened by 0.22 GHz. The same bandwidth expansion effects, however, are not observed along the other two axes. In addition, it is feasible to obtain two isolated frequency bands with negative permeability by combining SRRs along three axes.