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。     

Light Scattering by Cylindrical Fibers with High Aspect Ratio Using the Null‐Field Method with Discrete Sources

The problem of computing light scattering by cylindrical fibers with high aspect ratio in the framework of the Null‐Field method with discrete sources is treated. Numerical experiments for investigating the scattering properties of two fiber geometries are performed using distributed spherical vector wave functions as discrete sources.     

沿非线性界面传输的TM波传播常数的解析解

本文得到了沿一线性介质与非线性介质界面传输的ＴＭ波精确的色散关系和传播常数的解析计算公式，导出了计算非线性介质中传输功率流的积分公式。本文方法计算传播常数及功率流的优点是可不必先知道电场分布。     

Spectroscopic studies of new model compounds for poly[N,N′-bis(phenoxyphenyl)pyromellitimide]

New model compounds for poly[N,N′-bis(phenoxyphenyl)pyromellitimide] have been synthesized in order to investigate the formation of imine bonds which are proposed to form during the curing process and lead to crosslinking in the bulk polymer. Raman studies show that terminal amines can react with imide carbonyls during curing to form C?N bonds. The Raman band due to C?N appears at 1656 cm^?1 and the band due to C?O closest to the imine bond is observed at 1742 cm^?1. These results are in agreement with previously published results on vapor deposited polyimide films.     

Analysis of Radiation Phenomena in a Wedge Ended Dielectric Slab Waveguide

Radiation phenomena observed in a wedge shape ended dielectric slab waveguide are analyzed using mode matching technique. The case of transverse electric polarization (TE) being parallel to dielectric slab waveguide is assumed. In order to describe the fields in the wedge region, a stack of dielectric plates is assumed and in each layer the fields are expanded in terms of the mixed spectrum of guided and radiated modes. A similar expansion is used in the constant thickness slab waveguide while in free space medium a continuous-radiation mode expansion is used. Then a mode matching approach is applied, incorporating the orthogonality properties of mixed spectrum modes, in order to compute the wave fields inside the dielectric slab waveguide and wedge medium. Mode matching is achieved by discretizing the continuous radiation mode spectrum leading into a numerically stable solution provided a sufficient large number of points are used to convert integrals into finite summations. Numerical computations are carried out for various wedge geometries and shapes including linear and exponential profiles.     

介质光波导的数值计算及近似方法

综述介质光波导中模式分析方法的最新进展。着重分析严格的数值分析方法及近似方法最近的研究进展。依据方法的计算精确度、计算效率和计算复杂度等因素．对有限元法和有限差分法这两种数值分析方法以及有效指数法和频谱指数法等近似方法进行讨论。论述磁光波导的分析方法。     

FexNi100−x nanometric films deposited by laser ablation on SiO2/Si substrates

Fe_xNi_100−x nanometric films were deposited on SiO₂/Si substrates at room temperature using the pulsed laser deposition technique. The targets were Fe-Ni amorphous magnetic foils with composition Fe₅₀Ni₅₀, Fe₃₅Ni₆₅ and Fe₂₂Ni₇₈. Morphological and structural properties of the deposited films were investigated using scanning electron microscopy, Rutherford backscattering spectrometry, grazing incidence X-ray diffraction, and X-ray reflectivity. Electrical and magnetic characteristics of the films were investigated by using the four-point probe and the magneto-optic Kerr effect techniques, respectively. The film properties are strictly dependent on the Fe-Ni compositional ratio.     

Dispersion Characteristics of Waveguide Arrays in Optical Spectrum Analyzers

Formulas for calculating the spectral characteristics of waveguide arrays, which are incorporated into waveguide spectrum analyzers based on planar waveguides, channel waveguides, and fiber optical waveguides, are derived taking into account the contribution of both the waveguide dispersion and the material dispersion to the dispersion factor. These formulas are used to study the dependence of the dispersion factor on the waveguide-system parameters for specific models of waveguide arrays. It is shown that consideration of contributions of the waveguide dispersion and material dispersion can affect profoundly the spectral characteristics of waveguide arrays.     

A DC excited waveguide multibeam CO2 laser using high frequency pre-ionization technique

High power industrial multibeam CO₂ lasers consist of a large number of closely packed parallel glass discharge tubes sharing a common plane parallel resonator. Every discharge tube forms an independent resonator. When discharge tubes of smaller diameter are used and the Fresnel numberN ≪ 1 for all resonators, they operate in waveguide mode. Waveguide modes have excellent discrimination of higher order modes. A DC excited waveguide multibeam CO₂ laser is reported having six glass discharge tubes. Simultaneous excitation of DC discharge in all sections is achieved by producing pre-ionization using an auxiliary high frequency pulsed discharge along with its other advantages. Maximum 170 W output power is obtained with all beams operating in EH₁₁ waveguide mode. The specific power of 28 W/m is much higher as compared to similar AC excited waveguide multibeam CO₂ lasers. Theoretical analysis shows that all resonators of this laser will support only EH₁₁ mode. This laser is successfully used for woodcutting