线性对称耦合器的几何表示

利用线性对称耦合器两个波导中光场的电矢量构建了布洛赫矢量模型.通过布洛赫矢量的旋转变化使得光在两个波导通道中“跃迁”的过程非常直观.研究发现,随着线性对称耦合器的相位失配变得越严重,光能量在波导间的转换频率增快且转换效率降低,与传统的求解线性对称耦合器耦合波方程所得到的结果是一致的.     

一种新型的光纤锥形耦合器

提出了一种光纤波导折射率渐变的新型锥形（Taper）耦合器件，其原理是基于光纤中Ge缺陷在紫外光照射下而产生的光致折射率的变化。利用光纤在高压、低温下渗氢技术使单模光纤的光致折射率变化△n达6×10-3数量级；通过控制曝光条件就可以在光纤中产生一定规律的锥形结构，使单模光纤的模场半径由4．8μm缩小到3．2μm。由耦合波理论分析表明该器件具有较好的基模传输特性。     

高消光比定向耦合器开关设计

首先对对称结构定向耦合器的原理作介绍,分析造成该定向耦合器消光比降低的各种影响因素,提出一种带补偿电极的对称结构定向耦合器的设计方案.这一方案可以补偿制造工艺过程中的误差对耦合器的不良影响,提高耦合器的消光比.     

变耦合系数非线性三波导定向耦合器特性研究

报道了对高斯型及指数型变耦合系数三波导耦合器的一些重要的全光开关特性进行的研究。利用四阶龙格一库塔方法对指数型和高斯型两类变耦合系数三波导耦合器进行了数值计算。数值计算结果表明：对于变耦合系数三波导耦合器而言,功率可在波导1与波导3之间100％转换,而波导2则不可能达到100％的功率输出。与双波导变耦合系数耦合器相比,在相同的最大耦合系数情况下三波导变耦合系数耦合器开关曲线要更陡一些．即具有更好的开关特性。与平行三波导耦合器相比,变耦合系数三波导耦合器作为光开关的最大优点在于开关曲线中不存在振荡。     

三芯非线性光纤耦合器中的短脉冲光开关

利用变分法研究三芯非线性光纤耦合器中的短脉冲光开关,解析分析线性三耦合非线性Schr?dinger方程的结果与数值模拟符合得很好.并且得到在非线性光纤耦合器中孤子的耦合长度和开关阈值,与连续波情况和两芯光纤耦合器的结果不同. 关键词： 光纤耦合器 光开关 耦合长度 开关阈值     

带补偿电极的高消光比定向耦合器开关

研究了对称结构定向耦合器开关的工作原理 ,用正交模理论结合制造工艺条件分析了影响对称结构定向耦合器开关消光比的因素。提出了提高对称结构定向耦合器开关消光比的方法。理论分析及模拟计算结果表明 :在对称结构定向耦合器开关的分支区加上一对补偿电极后可以获得较高的消光比。     

对称结构光纤光栅耦合器及其应用

光纤光栅耦合器(FGC)具有光纤光栅良好的波长选择特性和光纤耦合器的多端口特点，易于实现全光纤的光波分插复用。光纤光栅耦合器主要有4种结构：基于M Z干涉仪的分离型、基于100％耦合器的非对称型、基于0耦合器的非对称型和基于100％耦合器的对称型。着重介绍对称结构光纤光栅耦合器的结构、工作原理和研究现状。提出了测试方案，并探讨了这种器件在大规模波分复用光纤传感器阵列中的应用。     

线性分子对称群的不可约表示和f轨道的对称性

研究了Ｃ∞ｖ和Ｄ∞ｈ群的不可约表示，并志出了在Ｃ∞ｖ，Ｄ－∞ｈ，Ｃ２ｖ和Ｃ３ｖ群中ｆ轨道所属的对称性。     

非宇称时间对称耦合器中的非局域孤子

研究了非宇称时间对称复数势下非线性耦合器中多类型非局域孤子的存在性和稳定性,发现基态孤子、偶极孤子、多极孤子分别从线性谱中不同的离散特征值分叉出来形成孤子族,其功率受非局域程度和传播常数的影响.在相变以下,各个类型孤子均在相对较低功率区间是稳定的.随着非局域程度的增加,基态孤子族的稳定区域变小,其他孤子族的稳定区域则变大.在相变以上,基态孤子则在相对中功率区是稳定的,并且从第二大离散特征值分叉出的偶极孤子不存在稳定区域.孤子线性稳定性分析结果中的特征值总是以共轭对的形式出现.此外,还研究了耦合系数对孤子态的影响.     

星形光波导耦合器的耦合特性分析

根据TE0模光波导的本征场分布、瑞利索末菲标量衍射积分公式和激励源与光波导耦合的匹配效率公式,给出光波导端面衍射和耦合的归一化发射系数和接收系数计算公式,推导出光波导端面非接触耦合的耦合效率计算公式。光波导模场分布采用高斯函数近似表达,给出简洁的计算光波导端面非接触耦合的耦合效率函数表达式。最后,基于星形光波导耦合器结构参量的特点,将累加运算采用积分运算近似表达,给出星形光波导耦合器接收光波导总的接收效率与耦合器基本参量的关系,阐明了星形光波导耦合器的耦合特性。     

On the Representation of the Symmetric and Alternating Groups by Fractional Linear Substitutions

Contents Introduction 1. The Representation Groups of the Groups S_n and A_n 2. On the Classification of the Elements of the Groups T_n and B_n into Classes of Conjugated Elements 3. On the Assignment of the Elements of the Groups S_n and T_n 4. General Properties of the Characters of the Groups T_n and B_n 5. On the Collineation Groups Belonging to the Characters of the Groups T_n and B_n 6. The Principal Representation of Second Kind of the Group T_n     

Graphical Representation of the Supermode Theory of a Waveguide Directional Coupler

A novel graphical representation of the supermode theory of a waveguide directional coupler based on phasor analysis is described. Following this approach, dependence of the magnitudes and phases of the output fields on the splitting ratio of a directional coupler is discussed. Both the cases of phase-matched (identical) and non-phase-matched (non-identical) waveguides constituting a directional coupler are investigated. This approach directly illustrates the fact that the phase shift suffered by the coupled light relative to the throughput light is π/2, regardless of the splitting ratio for identical guides, which is not the case for couplers with non-identical waveguides. It also yields additional information about the phases of the output fields of a directional coupler. The usefulness of this approach in the context of wavelength-flattened couplers, wavelength division multiplexing couplers, and polarization effects in directional couplers is also discussed. This approach should also be helpful in the analysis of guided wave interferometric devices such as wavelength interleave filters and modulators, based on concatenated directional couplers.     

A Geometrical Representation of Entanglement as Internal Constraint

We study a system of two entangled spin 1/2, were the spin's are represented by a sphere model developed within the hidden measurement approach which is a generalization of the Bloch sphere representation, such that also the measurements are represented. We show how an arbitrary tensor product state can be described in a complete way by a specific internal constraint between the ray or density states of the two spin 1/2. We derive a geometrical view of entanglement as a “rotation” and “stretching” of the sphere representing the states of the second particle as measurements are performed on the first particle. In the case of the singlet state entanglement can be represented by a real physical constraint, namely by means of a rigid rod.     

Concrete Representation and Separability Criteria for Symmetric Quantum State

Using the typical generators of the special unitary groups S U(2), the concrete representation of symmetric quantum state is established, then the relations satisfied by those coefficients in the representation are presented. Based on the representation of density matrix, the PPT criterion and CCNR criterion are proved to be equivalent on judging the separability of symmetric quantum states. Moreover, it is showed that the matrix Γ _ρ of symmetric quantum state only has five efficient entries, thus the calculation of ∥Γ _ρ ∥ is simplified. Finally, the quantitative expressions of real symmetric quantum state under the ∥Γ _ρ ∥ separability criterion are obtained.     

精确几何单元下弹性薄体结构问题的边界元法分析

对圆弧单元下的几乎奇异积分,采用变量替换法进行正则化,然后采用通常的高斯求积公式进行计算,可获得相当高的计算精度,即使是超薄的薄体结构,方法仍然十分有效.     

Integral Representation of the Linear Boltzmann Operator for Granular Gas Dynamics with Applications

We investigate the properties of the collision operator Q associated to the linear Boltzmann equation for dissipative hard-spheres arising in granular gas dynamics. We establish that, as in the case of non-dissipative interactions, the gain collision operator is an integral operator whose kernel is made explicit. One deduces from this result a complete picture of the spectrum of Q in an Hilbert space setting, generalizing results from T. Carleman (Publications Scientifiques de l’Institut Mittag-Leffler, vol. 2, 1957) to granular gases. In the same way, we obtain from this integral representation of Q ⁺ that the semigroup in L ¹(ℝ³×ℝ³,dx ⊗ dv) associated to the linear Boltzmann equation for dissipative hard spheres is honest generalizing known results from Arlotti (Acta Appl. Math. 23:129–144, 1991).     

Entangled Qubit States and Linear Entropy in the Probability Representation of Quantum Mechanics

The superposition states of two qubits including entangled Bell states are considered in the probability representation of quantum mechanics. The superposition principle formulated in terms of the nonlinear addition rule of the state density matrices is formulated as a nonlinear addition rule of the probability distributions describing the qubit states. The generalization of the entanglement properties to the case of superposition of two-mode oscillator states is discussed using the probability representation of quantum states.     

Derivation of Discrete Symmetric Transformations of Quantum Fields in View of the Linear Quantum Transformation Theory

In this paper, by using the linear quantum transformation theory (LQT), we derive all of the expressions of discrete symmetric transformations C, P and T for scalar field, electromagnetic field and Dirac field, respectively. So the superiority of LQT is showed here.