非理想同轴线的简正孪生模式及其复传播常数的近似解法

本文严格地分析了非理想同轴线中的简正波型，重点讨论了传输线模ＥＨｏｏ模以及常用的ＥＨｏｐ模和ＨＥｏｐ模（ｐ≥１），并对其截止频率进行变分分析，从而导出复传播常数的公式，结果表明，对于常用的ＥＨｏｏ模和ＥＨｏｐ的模，功率损耗法得出的衰减常数是本文公式实部的近似。

复折射率光纤传输特性的微扰分析

运用微扰分析方法计算复折射率光纤复传播常数 .光纤的复数模折射率N =N′ +iN″的实部N′由求解相应的实本征值方程得到 ,而虚部N″则由微扰计算得到 .对阶跃型圆光纤 ,导出了芯区或包层为复折射率时的损耗或增益的解析关系式 ,数值计算结果表明 ,本法与直接解复本征值方程得到的精确结果符合得很好 .

有增益及损耗的平板波导导模的精确微扰分析

给出求含有增益层与损耗层的突变与渐变折射率剖面多层平板波导导模的微扰理论与解析计算公式。举例讨论了导模模式的增益（或损耗）与结构参数和偏振的关系。本文方法较求解复本征值的打靶法等简便且节省机时。对于（半导体激光器与半导体激光放大器等）实际遇到的波导结构能给出精确数值结果，并可用以分析材料的增益系数或损耗对ＴＥ和ＴＭ模式及其增益的影响等问题。

The effective propagation constants of SH wave in composites reinforced by dispersive parallel nanofibers

In the present paper, the effective propagation constants of elastic SH waves in composites with randomly distributed parallel cylindrical nanofibers are studied. The surface stress effects are considered based on the surface elasticity theory and non-classical interfacial conditions between the nanofiber and the host are derived. The scattering waves from individual nanofibers embedded in an infinite elastic host are obtained by the plane wave expansion method. The scattering waves from all fibers are summed up to obtain the multiple scattering waves. The interactions among random dispersive nanofibers are taken into account by the effective field approximation. The effective propagation constants are obtained by the configurational average of the multiple scattering waves. The effective speed and attenuation of the averaged wave and the associated dynamical effective shear modulus of composites are numerically calculated. Based on the numerical results, the size effects of the nanofibers on the effective propagation constants and the effective modulus are discussed.