费米折射率波导的包层吸收模谱特性和溶液浓度传感研究

采用0.004AgNO3-0.996NaNO3混合熔融盐,用离子交换技术在德国B270光学玻璃上制备了费米折射率分布渐变波导,理论分析了费米折射率分布渐变波导的包层吸收模谱特性.导波损耗测试实验验证了解析结果.在此基础上,提出了一种用于液体包层吸收损耗测试的双样品盒串连的波导回路.测试结果证实表征溶液包层吸收特征的折射率虚部与溶液浓度之间具有十分显著的线性关系,测试灵敏度与波导的模式和波导参量有关,尤其与波导层厚度有非常敏感的关联性.利用这个关系传感测试了13种不同浓度的耐晒果绿染料水溶液样品的浓度,结果显示测试值与实际配制浓度值的均方差小于0.07%.     

全电极脊形波导光传输特性

给出一种较为简便的全电极脊形波导的分析方法,即采用有效折射率方法把此金属包层脊形波导化成一个二维等效平板波导,然后利用微分法得到模的有效折射率满足的方程和吸收损耗系数的解析表达式.作为一个特例,用这种方法对SiO2全电极脊形波导光传输特性如光传播常数和损耗进行了计算, 并得到一些有益的结论.     

非线性薄膜波导TE模色散特性的多层分割法计算

对于芯区为非线性介质、衬底及包层为线性介质的平板波导、提出用多层分割法分析芯区的模场,采用递推公式（等效于推广的传递矩阵法）求解传播常数与光功率间的依赖关系,该法适用地克尔型或非克尔型介质及芯区折射率非均匀的一般情形,实例计算结果与已有的精确数值计算结果十分符合。     

多层线型分割法分析渐变型平板介质波导

提出了一种求解渐变折射率平板光波导的传播常数和场强分布的数值计算方法,计算了几类典型的渐变折射率波导的传播常数数值,并与其它方法进行了比较,结果表明,该方法计算的精度极高,速度较快,有实用价值.     

有机-无机复合ZrO2-SiO2平面光波导

采用溶胶-凝胶法合成ZrO2-SiO2有机一无机复合光波导材料,通过改变其中ZrO2的含量来调节材料的折射率,使材料分别适用于平面光波导的导光层(ng≈1．497)和衬底层、包层(mb=nc≈1．479)。采用旋转涂膜工艺和相应的热处理,在单晶硅基片上制备衬底层、导光层和包层等薄膜,其中导光层介质因具有感光性而可通过紫外光刻来制备光路图案。所得有机一无机复合ZrO2-SiO2板型平面光波导(衬底层 导光层),用棱镜耦合截断法测试其光损耗在632．8nm波长处约为0．8dB／cm。对板型平面波导的导光层薄膜进行紫外光刻和异丙醇淋洗,制备出脊状光波导通道,在覆盖包层后,即获得埋层沟道式平面光波导。采用端耦合截断法测试了埋层沟道式平面光波导的光损耗(小于0．1dB／cm),并观察了其近场图像以及导光材料在近红外窗口的吸收光谱。     

双平行圆柱形MDM纳米棒等离子体波导的传输特性分析

设计了一种由双平行圆柱形纳米棒构成的金属-介质-金属(MDM)型等离子体波导,采用时域有限差分方法(FDTD)分析了波导结构的传输特性。当光波垂直主轴入射时,电磁场被很好地局限在两纳米棒所形成的中间区域以及介质层中,从而在该波导中能够有效地耦合电磁场能量。在工作波长为1 550 nm的情况下,随着内层金属芯半径的增大,有效折射率减小,传播距离增大;而中间介质层厚度增大时,有效折射率增大,传播距离减小。当外层金属壳厚为20 nm时,电场可以很好地被限制在纳米棒的介质层内。上述结果表明:通过调整波导结构的几何参数可以显著提高金属纳米棒的场限制,降低波导本身的损耗, 使波导的有效折射率和传播长度达到最优化。这种等离子体波导能够实现亚波长的光限制,可以应用于光子器件集成和传感器领域。     

多层线型分割法分析渐变型平板介质波导

提出了一种求解渐变折射率平板光波导的传播常数和场强分布的数值计算方法，计算了几类典型的渐变折射率波导的传播常数数值，并与其它方法进行了比较，结果表明，该方法计算的精度极高，速度较快，有实用价值。     

扩散平面光波导的传递函数方法

引入一种计算光波导传播特性的新方法传递函数方法。给出了公式推导,计算了扩散各向同性及扩散各向异性平面光波导的传播特性,并与其它方法所得结果进行了比较。结果表明用传递函数方法处理折射率渐变分布的光波导问题,计算相对简单,可以得到精确的数值结果。     

金属包覆极化聚合物光波导的优化设计

按极化聚合物光波导器件的五层（金属－缓冲层－波导层－缓冲层－金属）对称模型，对于其金属包覆层的光学吸收所引起的光波传播损耗进行了理论分析和计算，给出了在单模条件下波导层和缓冲层折射率及其厚度之间的关系曲线，计算确定出单模极化聚合物光波导参数。     

聚硅氧烷改性及多模光波导制备

采用含氢聚硅氧烷(HPSO)和二乙烯基苯(DVB)的交联体掺入聚二甲基硅氧烷(PDMS)中,使改性的聚二甲基硅氧烷(M-PDMS)折射率发生1%～1.8%的改变。M-PDMS及PDMS薄膜具有良好的光透射率和低的传输损耗,是低成本制备用于高速芯片间光互连聚合物光波导的理想材料。采用软成型和图案转移法,用M-PDMS及PDMS分别作波导的芯层和包层制备了截面为50μm×50μm,长度大于20cm的聚硅氧烷多模光波导。用数字化散射法测量了所制备波导的传输损耗,测得输入光波长为633nm时平均传输损耗为0.137dB/cm。     

渐变折射率波导传播特性微扰计算的代数递推公式

应用量子力学的超位力定理（HVT）和赫尔曼－费恩曼（Hellmann-Feynman）定理（HFT），导出了用微扰法计算渐变折射率平面波导传播常数各级近似值的代数递推公式，并给出了由传播常数近似值计算模场近似表达式的代数式。计算了几个典型实例，此法的特点是便于直接计算任意级近似的传播常数及模场分布，且可推广到二维波导的计算。     

一种水平变化波导中声传播问题的耦合模态法

针对介质参数及海底边界水平变化波导中的声传播问题,本文基于多模态导纳法提出一种能量守恒且便于数值稳定求解的耦合模态方法.将声压表示为一组正交完备的本地本征函数之和,对声压满足的Helmholtz方程在本地本征函数上作投影,推导出关于声压模态系数的二阶耦合模态方程组.耦合矩阵直观描述水平变化因素对模态耦合的贡献.为避免直接求解二阶耦合模态方程组可能遇到的数值发散问题,将其重构为两个耦合的一阶演化方程组,引入导纳矩阵并使用Magnus数值积分方法获得稳定的声场解.利用该耦合模态方法数值计算水平变化波导中的声场,并与COMSOL参考解比较,结果表明该耦合模态理论能够精确求解水平变化波导中的点源及分布源传播问题.     

Propagation-mode near-field method for measuring optical waveguides of graded index profile: some considerations on TM-modes

A new set of formulae is developed for profiling refractive index of optical waveguides using the propagation-mode near-field method. Effects of graded-index profile on wave equations for TM-modes are taken into account. Anisotropic waveguides are also studied.     

Analysis of non-linear multilayer waveguides with Kerr-like permittivities

This paper presents a semi-analytical method for calculating the dispersion relationships for stationary non-linear TE waves guided by general multilayer waveguides with Kerr-like permittivities. The non-linear wave equations are solved rigorously for each layer, and the mode index and field distribution are systematically determined so as to satisfy the boundary conditions at all interfaces. To verify the validity of the present method, a non-linear graded-index waveguide is approximated by a number of step layers and the resultant multilayer waveguide is analysed numerically. The convergence properties of mode index and total power flow are presented, and these are compared with direct solutions of the non-linear wave equation by the numerical integration method. The dispersion relationships for a non-linear multiple-quantum-well waveguide have also been investigated under two simple permittivity models. The present method is useful for the analysis of non-linear graded-index waveguides in addition to non-linear multilayer waveguides such as the multiple-quantum-well structure.     

Propagation and radiation characteristics of the circular electric, circular magnetic and hybrid waveguide modes

The field distributions and propagation constants of the circular electric, circular magnetic and hybrid modes of oversized waveguides are expressed, taking the effects of walls into account. These effects are described by wall functions which depend on surface impedances of the wall, and are determined for different types of guides. The near and far field patterns are derived in the case of real wall functions. It is shown that, for very oversized waveguides, the terms containing wall functions can be ignored in the calculations, and it results that the expressions of fields and propagation constants become independent of the types of waveguides. An application to corrugated waveguides for Electron Cyclotron Resonance Heating experiments shows the variations of the radiation characteristics versus geometric parameters of the corrugations and determines the ranges of interest for these parameters.     

大截面单模半导体脊形交叉波导传输特性

运用光束传播法和有效折射率法分析了大截面单模半导体脊形交叉波导结构的传输特性，对Ｙ形，Ｘ形和加宽Ｘ形结构进行了比较。结果表明，在小交叉角时，三种结构具有相似的传输特性；在大交叉角时，它们表现出较大的差异。而在Ｙ型结构中，不存在模式干涉。     

Exact and Analytical Methods for Finding Complex Roots of Moving Waveguides with Absorbing Layers

We present here two methods of analysis of the complex moving waveguide. One approach is a numerical technique based on Davidenko's method, the other is a perturbation method. Numerical results by Davidenko's method are compared with these obtained from the perturbation method. It is found that the results of the perturbation method are in a good agreement with the numerical one. A comparative study of the propagation and attenuation characteristics of the stationary and moving waveguides has also been investigated and discussed. These results could be used in designing many optical moving sensors.     

Structural and optical properties of waveguides in YbVO4 crystals formed by 3.0 MeV Cu-ions implantation

We report on the structural and optical characterization of waveguides formed in YbVO₄ crystals by Cu²⁺-ion implantation with an energy of 3.0 MeV and doses of 3.0×10¹⁴-1.0×10¹⁵ ions/cm². The damage properties are determined by RBS/Channeling measurements with the help of simulation code RUMP. The m-line method is used to characterize the dark-mode spectroscopy in the planar waveguides. According to the reconstructed refractive index profile of the waveguide cross section, a numerical simulation is carried out to investigate the confinement of the light in the waveguides based on the beam propagation method.     

A full-wave three-dimensional analysis of open dielectric waveguides and periodic structures using an equivalent network model

An accurate fully vectorial wave analysis to calculate the propagation characteristics and field distribution of open dielectric waveguides and optical integrated circuits is presented. Based on the periodic repetition concept and using an equivalent network model, a method to analyze wave propagation in these guides is developed, which is able to take the simultaneous presence of mixed polarizations into account. Compared with conventional approaches like mode matching as well as with other numerical methods, the presented three-dimensional (3D) method shows individual advantages like accuracy, simplicity, and numerical efficiency. To show both validity and usefulness of this approach, some fundamental structures are investigated and the obtained numerical results are presented.