平板波导谐振腔耦合损失的衍射理论

计算了一板波导谐振腔的耦合损失，给出了平板波导中ＥＨ１１模的耦合损失与球镜的曲率及位置的关系。计算结果表明存在两种特定的结构使耦合损失最小。     

平板波导谐振腔耦合损失的厄米高斯展开分析法

平板波导内的场按自由空间传播的厄米高斯函数展开，计算了平板波导谐振腔的耦合损失，给出了平板波导中ＥＨ１１模的耦合损失与球镜的曲率及位置的关系。结果表明存在两种特定的结构使耦合损失最小。     

利用波叠加观点讨论光波导模式的物理意义

不同于传统的光波民模式理论，本文从光波叠加的观战分析了光波导中形成光场模式的机制，给我场模式的物理定义，用普通物理方法计算了平面光波导中模式的场分布，并给出了特征方程以及一些波导参量的物理意义。     

有限差分光束传输法的分析

结合辐射可透边界条件，由Ｍａｘｗｅｌｌ方程导出了ＴＥ模和ＴＭ模的ＦＤ－ＢＰＭ法基本公式，通过对数值误差引起的计算损耗和传播常数的误差分析，对算法进行了评估。     

求复折射率波导本征值的打靶法

给出了求一维缓变复折射率波导本征值的打靶法，它是对求一维实折射率波导本征值的打靶法的推广，利用它可以分析增益或损耗对ＴＥ和ＴＭ模式的影响，并给出了计算实例。     

有损耗介质中非线性光导波的数值模拟

发展了一种以有限元法为基础的数值方法，用它分析由损耗任意大小材料构成的平面非线性波导结构所传导的非线性有损耗光波。在这种方法中，从给出的非线性有损耗波导直接得到ＴＥ和ＴＭ波与功率有关的复传播常数和局域电磁场分布。     

用有效折射率／有限元法设计1．55μmTi：LiNbO_3单模条波导及其方向耦合器

应用有效折射率／有限元法（ＥＩ－ＦＥＭ），考虑到ＬｉＮｂＯ３晶体和Ｔｉ扩散的各向异性，折射率增量与寻常光、非寻常光及波长色散的关系，设计了１．５５μｍ光波长下工作的ｚ切ｙ传播Ｔｉ：ＬｉＮｂＯ３单模条波导的制备参数，计算和分析了其单模特性、模式场分布及其变化规律．扩展了ＥＩ－ＦＥＭ，将其用于求解耦合波导系统，确定了方向耦合器的耦合长度及其波长色散特性．     

离子交换KTP晶体光波导及其各向异性波导性能研究

采用离子交换法制备了Ｒｂ：ＫＴＰ晶体光波导，在不同波长的耦合光下测量了ＴＥ和ＴＭ偏振波导模式的有效折射率，拟合了波导层折射率的余误差函数分布，证明了波导折射率增量的各向异性，给出了其色散关系；最后计算并讨论了Ｒｂ：ＫＴＰ波导的扩散特性。     

远红外波导FEL振荡器的数值模拟

利用ＦＥＬＯ８程序对远红外ＦＥＬ振荡器进行数值模拟，验证了２００ｐｍＦＥＬ的可行性，得到初始小讯号增益２５％，±１１０ｐｓ范围内的电子束时间间隔晃动对激光功率和小讯号增益影响不显著。     

双包层椭圆光波导解析解

解析求解了双包层椭圆光纤中的波动方程，得到了模式精确解有模式特征方程。对基模的特征方程进行了数值计算，给出了不同椭圆比下的归一化双折射和模间色散随归一化频率的变化关系曲线，并与高斯近似解的结果进行了比较。     

低差分模式时延少模光纤的有限元分析及设计

针对少模光纤展开研究, 利用Comsol软件计算其模场分布、有效折射率, 进而分析光纤的差分模式时延. 通过分析不同结构参量对模式数量和差分模式时延的影响, 设计出了两种低差分模式时延的少模光纤, 即带有外下陷的渐变式光纤和多阶少模光纤. 波长在1530–1570 nm 范围内, 带有外下陷的渐变式光纤支持四模传输, LP₁₁, LP₂₁, LP₀₂模式的差分模式时延的绝对值小于0.015 ps·m^-1; 多阶少模光纤支持两模传输, LP₁₁的差分模式时延低于0.185 ps·m^-1. 两种少模光纤均具有良好的差分模式时延特性, 适于在模分复用技术中应用.     

Minimalist and convenient mode changing off-axis digital holography

Basic issues in creating practical setups for off-axis digital holography involve having (i) convenient switch of imaging in the transmission and reflection modes, (ii) reduction in stray light reflection, (iii) immunity against environmental noise, and (iv) efficient usage of light output from the laser source. These exigencies are addressed using a free-space setup described here that applies a minimal number of optical components. Experimental results are presented to verify the approach.     

浅海波导中折射类简正波的warping变换

Warping变换可以实现单水听器浅海低频声波导的简正波分离.本文讨论了海水声速随深度线性减小浅海波导中折射类简正波的warping变换.理论推导了海水折射类简正波水平波数、频域相位及瞬时相位的表达式,由此提出了相应的时域和频域warping变换算子,并由仿真数据进行了验证.本文的理论推导过程同样适用于海水声速线性增大或海水折射系数的平方随深度线性变化的浅海波导.     

Linear analysis of plasma pressure-driven mode in reversed shear cylindrical tokamak plasmas

The linear behavior of the dominant unstable mode ($m=2$, $n=1$) and its high order harmonics ($m=2n$, $n\ge 2$) are numerically investigated in a reversed magnetic shear cylindrical plasma with two $q=2$ rational surfaces on the basis of the non-reduced magnetohydrodynamics (MHD) equations. The results show that with low beta (beta is defined as the ratio of plasma pressure to magnetic field pressure), the dominant mode is a classical double tearing mode (DTM). However, when the beta is sufficiently large, the mode is driven mainly by plasma pressure. In such a case, both the linear growth rate and mode structures are strongly affected by pressure, while almost independent of the resistivity. This means that the dominant mode undergoes a transition from DTM to pressure-driven mode with the increase of pressure, which is consistent with the experimental result in ASDEX Upgrade. The simulations also show that the distance between two rational surfaces has an important influence on the pressure needed in mode transition. The larger the distance between two rational surfaces, the larger the pressure for driving the mode transition is. Motivated by the phenomena that the high-$m$ modes may dominate over low-$m$ modes at small inter-resonance distance, the high-$m$ modes with different pressures and $q$ profiles are studied too.     

钛酸盐ATiO3钙钛矿的铁电和反铁畸变

钛酸盐钙钛矿氧化物体系的研究对理解具有铁电极化的功能材料具有非常重要的科学意义.本文对ATiO3(A=Ca,Sr,Ba,Pb,Cd)体系的低温相、结构相变、及其对应的位移模式进行综述.我们着重比较了该体系存在的两类不稳定声子模式,即铁电极化模式(Ferroelectric,FE)和反铁畸变模式(Antiferrodistortive,AFD),在不同体系中所起到的作用.我们举例阐述了晶格失配应变、人工构造超晶格和化学掺杂等方法对这两种模式的调控思路.最后我们给出本文的总结讨论及研究展望.     

钛酸盐ATiO3 钙钛矿的铁电和反铁畸变

钛酸盐钙钛矿氧化物体系的研究对理解具有铁电极化的功能材料具有非常重要的科学意义.本文对ATiO3(A= Ca,Sr,Ba,Pb,Cd)体系的低温相、结构相变、及其对应的位移模式进行综述.我们着重比较了该体系存在的两类不稳定声子模式,即铁电极化模式(Ferroelectric,FE)和反铁畸变模式(Antiferrodistortive,AFD),在不同体系中所起到的作用.我们举例阐述了晶格失配应变、人工构造超晶格和化学掺杂等方法对这两种模式的调控思路.最后我们给出本文的总结讨论及研究展望.     

半导体激光器与单模光纤耦合效率的分析

在高斯场分布近似的前提下,从模场半宽匹配的角度描述了半导体激光器（ＳＬＤ） 与单模光纤（ＳＭＦ） 之间的光耦合理论。对不同的ＳＬＤ ＳＭＦ 间光耦合的方式作了分析,并从耦合效率与成本双重角度给出了适合于实际工程应用的几种耦合方式的优选率     

环形ZnO薄膜谐振器的横模抑制与测试分析

采用Tiersten方程研究了环形ZnO薄膜谐振器中横模寄生问题, 获得了环(圆)形薄膜谐振器的横模振动方程, 求得横模位移场解和频率色散方程; 然后采用电磁学模式合成理论进行分析, 发现环形薄膜谐振器横模频率与环形电极的内外径之比a/b有关, 振动模式可由圆形薄膜谐振器横模模式合成得到, 通过控制a/b能够抑制横模模式数和调控基膜频率. 采用外差激光干涉仪和网络矢量分析仪测量并比较了同批次的圆形和环形薄膜谐振器的上电极横模振动图样和电阻抗曲线. 振动图样显示环形薄膜谐振器振动模式可由半径为a和半径为b的圆形薄膜谐振器振动模式合成, 仅存在节圆数大于0的横模振动, 等于0的横模模式被抑制; 电阻抗曲线显示当a/b为0.436时, 环形薄膜谐振器的基频(约1217 MHz)和圆形的(0, 1)模式频率相等. 测量数据验证了模式合成理论的分析结果正确性, 为薄膜谐振器的横模抑制研究提供了理论基础和新方法.     

Magnetically insulated transmission line oscillator oscillated in a modified HEM11 mode

This paper puts forward a novel magnetically insulated transmission line oscillator (MILO) for the first time which takes a modified HEM11 mode as its main interaction mode. The excitation of the oscillation mode is made possible by carefully adjusting the arrangements of each resonant cavity in a two-dimensional (2-D) slow wave structure. The high frequency characteristics are analyzed and a PIC simulation is carried out; the detailed results are discussed to get a better understanding of this new MILO. Employing an electron beam of about 441 kV and 39.7 kA, it finds that the modified HEM11 mode MILO generates a high power microwave output of about 1.47 GW at 1.45 GHz. The power conversion efficiency is about 8.4% and the generated microwave is in a TE11-like circularly polarized mode; its polarization direction is decided by the rotation direction of the SWS.     

Experiment and simulation of tearing mode evolution with electron cyclotron current drive in KSTAR

The tearing mode (TM) plasma instability was observed in low confinement (L-mode) plasmas when non-axisymmetric magnetic perturbation (MP) was applied using external coils during 2011 campaign of KSTAR. Based on the collected information of the magnetic island location in a plasma, a discharge was designed for suppression of a (2,1) TM mode by adjusting electron cyclotron (EC) launcher angles to the estimated island position. Here, the (m,n) notation describes the poloidal mode number and the toroidal mode number of the TM, respectively. The discharge is analysed with experimental observations and numerical simulations. Mirnov coil (MC) arrays and electron cyclotron emission (ECE) are used for analysis of the island width and the location as well as the mode number. The EC deposition and its alignment with the island are estimated by X-ray imaging crystal spectroscopy (XICS) and ECE measurements. An integrated numerical system is employed for modelling of this discharge to analyse a temporal evolution of the mode activity by integrating plasma equilibrium, transport, heating and current drive, and the magnetic island evolution, in a self-consistent way. The effect of EC current drive is discussed by comparing with another TM discharge but without ECCD. Some possibilities for classifying this mode to neoclassical tearing mode (NTM) and stabilisation effect of ECCD are suggested based on the experimental observation and the simulation results.