多层旋波媒质平板的反射与透射

本文先利用电磁场的边界条件导出平面电磁波垂直入射于多层平板旋波媒质的透射场表达式。然后用传输线理论中的阻抗法,解决了多层平板旋波媒质的反射问题。最后对多层旋波媒质平板的一特例－双层结构型旅波吸波材料进行了计算机辅助设计分析,分析表明,双层代替单层可以在一定程度上改善涂层的吸波特性。     

电导率对旋波介质吸波性能的影响

旋波介质的吸波性能与介质的手性参量有关,而手性参量又与介质的电导率有关。制备了4种不同电导率基底的旋波介质,根据自由空间测量旋波介质手性参量的方法,通过测量两次复反射系数、透射偏转角和椭偏率,计算得到介质的手性参量和吸波性能。结果表明,改变旋波介质基底的电导率,可以调节旋波介质的电磁性能和吸波性能,当基底的电导率为4.2×10–2 S/cm时,旋波介质的吸波效果最好,其反射系数的最小值达–24 dB。     

多光子Jaynes—Cummings模型的光子反聚束效应

在旋波近似下，分析了共振与非共振两种情况下多光子Ｊａｙｎｅｓ－Ｃｕｍｍｉｎｇｓ模型的光子反聚束效应及初始原子相干性对其影响。考虑非旋波近似，讨论了弱场短时间内的光子反聚束效应，得到了一些不同于旋波近似下的结论。     

非旋波近似下光场与级联型三能级原子相互作用系统的场熵演化特性

本文采用全量子化理论，研究了非旋波近似下级联型三能级原子与单模光场相互作用过程中受激场场熵的演化规律，通过与旋波近似下的相应结果进行比较，进一步揭示出非旋波近似下虚光场效应和初始场的平均光子数对场熵演化特性的影响．     

多光子Jaynes—Cummings模型的光子反聚束效应

在旋波近似下，分析了共振与非共振两种情况下多光子Ｊａｙｎｅｓ－Ｃｕｍｍｉｎｇｓ（Ｊ－Ｃ）模型的光子反聚束效应及初始原子相干性对其影响。考虑非旋波近似，讨论了弱场短时间内的光子反聚束效应，得到一些不同于旋波近似下的结论。     

不取旋波近似情形二能级原子的共振荧光谱

一般的二能级原子的共振荧光理论都是取旋波近似后得出来的．施波近似成立的前提是驱动场频率则，原子跃迁频率驱动场的Rabi频率．但在强场作用情形Rabi频率可达到同一量级．从实验角度来看，一千瓦级CW激光，功率密度为是可能的．按公式对3S－3P钠原子跃迁，可得．若采用COIL准连续激光，功率密度百千瓦量级，故达到是有希望的．故发展不取旋波近似的二能级原子共振荧光理论是有意义的．计算结果表明不取旋波近似的二能级原子的共振荧光显得很复杂．中峰出现分裂，而边峰也有一系列不对称的谐波．不取旋波近似情形二能级原子的共振荧光…     

一种基于神经网络提取旋波材料参数的新方法

提出了一种从测试的S参数中提取旋波材料参数的新方法——神经网络法。针对旋波材料参数的自由空间测试方法,本文采用BP神经网络来构建映射模型,利用不同算法对网络进行训练,从而获得所需的网络。结果表明,该方法计算速度快、精度高,解决了求解非线性方程组解的模糊性问题,确保了测试结果的可靠性。该方法所构建的网络可用于材料测试后旋波材料参数的快速提取。     

虚光场在原子的周期衰变和回复效应中的影响

本文利用非相对论量子电动力学理论,研究了在旋波近似(RWA)和非旋波近似下与双光子场作用的二能级原子算符的时间演化规律。 在旋波近似下,描述二能级原子与共振激光场相互作用的哈密尔顿量为:     

Fresnel区板天线辐射特性的矢量场分析

本文利用矢量场绕射理论分析研究Ｆｒｅｓｎｅｌ区板天线的辐射特性，并统一考虑馈源对天线增益、副瓣电平和交叉极化等参数的影响，所做工作适用于透射型和反射型Ｆｒｅｓｎｅｌ区板天线。天线远场方向图的计算和实测结果吻合较好，表明本文建立的Ｆｒｅｓｎｅｌ区板天线矢量场绕射模型的有效性。     

Fresnel区板天线辐射特性的矢量场分析

本文利用矢量场统射理论分析研究Ｆｒｅｓｎｅｌ区板天线的辐射特性，并统一考虑馈源对天线增益、副瓣电平和交叉极化等参数的影响，所做工作适用于透射型和反射型Ｆｒｅｓｎｅｌ区板天线。天线远场方向图的计算和实测结果吻合较好，表明本文建立的Ｆｒｅｓｎｅｌ区板天线矢量场绕射模型的有效性     

Power Reflection and Transmission Coefficients for Meander‐Line Polarizers with a Chiral Slab

This paper presents a theoretical investigation of power reflection and transmission coefficients for a meander‐line polarizer placed periodically on a chiral slab. It is assumed that a linearly polarized transverse magnetic wave is incident on a chiral slab from the air region. In the analysis, we derive the electric and magnetic fields in the modal form in the air and chiral regions. We obtain power reflection and transmission coefficients in a straightforward manner after matching the tangential components of the electric and magnetic fields at the boundaries. We present numerical results for the power reflection and transmission coefficients versus frequency and incident angle for different values of the chirality admittance. A meander‐line polarizer placed on a dielectric slab can convert a linearly polarized wave to a circularly polarized wave. The design parameters for a meander‐line polarizer are the dimensions of the meander‐line and the values of the dielectric slab. Replacing a dielectric slab with a chiral slab introduces a new independent parameter which controls the wave polarization.     

Vector circuit method applied for chiral slab waveguides

Eigenvalue equations for the propagation constants of lightwaves in open chiral slab waveguides are derived. The analysis makes use of vector circuit modeling of a chiral slab, the method which has been previously applied for calculating reflection and transmission of electromagnetic waves in chiral multilayer structures. The general eigenvalue equation for the guide which is valid for arbitrary boundary impedance conditions on the slab interfaces is derived, and three special cases are analyzed in detail: an open chiral dielectric slab with dielectric half spaces of the opposite sides of the slab, a chiral slab on an ideally conducting surface, and a chiral slab on an ideal magnetic surface. The theory is visualized by calculated dispersion curves indicating the chirality effect on the wave propagation characteristics     

斜入射情况下基于SHS的手征平板反射特性研究

从手征材料的本构方程出发,利用斜入射情况下基于SHS(softandhardsurfaces)的手征平板反射系数,对其特性进行了分析。然后推导计算了线性极化平面波斜入射到手征平板上的极化螺旋度向量,并对反射波的极化方式进行了分析。结果显示反射波的极化方式会发生改变,且反射波中含有交叉极化项。     

Ie transmission properties of stratified chiroferrite media with obliquely incident plane wave

A parameter study of electromagnetic wave propagating through the air-chiro ferrite inter face and through a chiro ferrite slab is presented, and such bianisotropic medium can be made from chiral and gyrotropic ferrite materials artifically. The partial differential equations of the fourth order defining the field components E_y and H_y in chiroferrite are derived. The influence of different constitutive parameters on the transmission coefficients and refraction angles of transmitted fields are demonstrated. The results show that chirality causes strong effect of energy conversion between mode 1 and 2.     

分层手征介质中电磁波的传播矩阵法及其传播特性研究

本文首先建立了任意分层手征介质中的电磁波传播矩阵法,给出了正向和反向传播矩阵的一股形式。并且分析了两种不同手征介质界面处,有无金属板衬底的单层手征介质板的反射和透射特性,特别考虑了手征导纳的影响。     

BI-FDTD: a novel finite-difference time-domain formulation for modeling wave propagation in bi-isotropic media

This paper presents a newly developed finite-difference time-domain (FDTD) technique, referred to as BI-FDTD, for modeling electromagnetic wave interactions with bi-isotropic (BI) media. The theoretical foundation for the BI-FDTD method will be developed based on a wavefield decomposition. The main advantage of this approach is that the two sets of wavefields are uncoupled and can be viewed as propagating in an equivalent isotropic medium, which makes it possible to readily apply conventional FDTD analysis techniques. The BI-FDTD scheme will also be extended to include the dispersive nature of chiral media, an important subclass of bi-isotropic media. This extension represents the first of its kind in the FDTD community. Validations of this new model are demonstrated for a chiral half-space and a chiral slab.     

Chiral slab polarization transformer for aperture antennas

The cross polarization of large aperture antennas can be eliminated by a chiral slab transformer in front of the aperture to obtain a more efficient field pattern. The inhomogeneous chirality distribution required can easily be achieved by using a mixture of right- and left-hand helices so that the total density of the helices is constant inside the slab. Reflection from the slab can be eliminated by a proper design     

单层磁性平板传输特性分析

探讨了单层有机磁性材料平板的传输特性。通过改变磁性材料参数,详细分析了单层平板的功率透射系数和插入相位移随平面波的入射角或随平板厚度的变化关系。数值结果表明,相对介电常数和相对磁导率相等的磁性平板具有最佳的电磁传输特性。     

Transient reflection properties of a dispersive and lossy bi-isotropic slab with an anisotropic laminated composite backing

This paper presents a detailed analysis of the transient reflection from a general bi-isotropic slab backed by a laminated composite. Either a nonreciprocally Tellegen medium or a reciprocally dispersive chiral medium with losses is considered as the bi-isotropic slab. The laminated composite is a graphite-fiber-reinforced-plastic composite (GFRPC), which has been widely used as a replacement for metals and may be treated as a multilayered anisotropic medium from the electromagnetic point of view. For the analysis, a theoretical model is developed based on a state-equation approach. On the basis of this model, both the time-domain and the frequency-domain plane-wave reflection results are obtained and studied. The factors affecting the results, such as the material parameters of the bi-isotropic slab and the fiber-orientation pattern of the GFRPC, are investigated in detail. Some special reflection properties, such as the twist-polarizer reflection and the antireflection, are observed based on this investigation. The properties may lead to a novel transient absorber technology for electromagnetic compatibility (EMC) applications.     

Si基槽型光波导的传输特性分析和传输损耗的测量

对Si基槽型(slot)光波导的传输特性进行了研究。 采用三 维时域有限差分(3D-FDTD)法研究了芯层中的光功率与波导槽型宽度及Si条带宽度之间的关 系,结果显示,槽型光波导具有很好的光功率约束效率,可以达到30%以上; 分析了光功率的变化规律及其优化,综合考虑光功率和光功率密度确定波导结构参数,实现 最佳光功率分 布,横向光功率分布沿x轴方向具有很好的约束效果,沿y轴方向呈现高斯分布;分析了底部Si薄层对光 功率的影响,100nm的底部Si薄层使得芯层的光功率下降50%,减小 底部Si薄层厚度有利于光功率约束效 率的提高;采用电子束刻写(EBL)技术和等离子刻蚀(ICP)技术制备了Si基槽型光波导,实验 研究了其传输损耗,结果显示,槽型光波导具有较低的传输损耗,达到13.5dB/cm。