高功率毫米波圆波导TM01—TE11模式变换分析

 在数值研究高功率毫米波TM₀₁—TE₁₁光滑弯曲圆波导模式变换的基础上，对弯曲波导的几何结构进行了优化分析。在模式耦合理论的基础上，优化出了比较好的几何结构，并发现了圆波导半径、弯曲圆波导曲率和频率以及频带宽度之间的变化规律。以此数据设计的模式变换器的转换效率可达99%，带宽超过29.8%。     

一种高品质中空金属光波导

讨论了高品质中空金属光波导的工作原理及其制作工艺，制备了以金和银作为波导材料的中空波导管，并对空芯以及充入不同透明液体的液芯波导的透光特性进行了测试，结果表明：与中空介质波导相比，中空金属波导具有光传输损耗低，透过率对波导弯曲与失调不甚敏感等优点；而液芯金属波导的透光效率与透明材料的折射系数无关。文中描述了在特定波段内“中空光纤”的原理，并报道了Ｈｅ－Ｎｅ和ＣＯ２激光在中空金壁波导传输的实验结果。     

一种可用于分析任意介电常数张量的各向异性波导导模的二维时域有限差分模型

为分析具有任意介电常数张量的各向异性波导的导模，本文通过把简化的二维时域有限差分（２－ＤＦＤＴＤ）法扩展至任意各向异性介质，提出了一种以Ｄ、Ｅ和Ｈ场为基础的统一的简化２－ＤＦＤＴＤ模型．利用该模型，研究了简化的复数２－ＤＦＤＴＤ方法与实变数２－ＤＦＤＴＤ方法之间的关系．文中还讨论了复变数方法和实变数方法的激励技术．     

Characteristic Study of the Periodically Iris-Loaded Elliptical Waveguide for Slow-Wave Structures

The slow-wave characteristics taking no account of space harmonics for periodically iris-loaded elliptical waveguides is presented. By using the field-matching method, the dispersion equation and the mean interaction impedance for odd and even hybrid modes of this structure are derived respectively. It is indicated from the numerical calculation results that changing the eccentricity can improve the dispersion characteristics and the interaction impedance for _oHEM₀₁ mode.     

Polarisation splitter/combiner based on an antiresonant directional coupler

The theoretical performance of a new polarisation splitter/combiner based on a directional coupler is studied using vectorial mode analysis. The device includes an efficient antiresonant mirror transparent to TM polarisation and opaque to TE polarisation. Simulations indicate a high level of TM light can be transferred from the input waveguide into the non-excited guide for coupling lengths shorter than 1 mm. In addition, coupling efficiency of 80% and extinction ratios close to 30 dB have been obtained in a not optimised device.     

非均匀平板波导的色散方程

利用转移矩阵理论分析了任意折射率分布平板波导的传输特性，导出了非均匀平板波导的近似解析色散方程，并指出了ＷＫＢ近似的局限性，数值比较的结果表明，文中所得公式的精确度优于传统的ＷＫＢ方法和其它近似方法。     

Thin films of peroxopolytungstic acids: applications to optical waveguide components

Thin films of peroxohetero(carbon)polytungstic acid (CW-HPA) and carbon-free isopolytungstic acid (W-IPA) were prepared, and examined in terms of optical and etching properties. Thermal decomposition was found to give good results in removing excess hydrogen peroxide (H₂O₂) during the preparation of CW-HPA and W-IPA. It was shown for the first time that thin films of CW-HPA and W-IPA have very high refractive indices (larger than 2.0) when sufficiently dried. Optical waveguide (OWG) characteristics of these films were examined using a slab-type OWG structure and ARROW (Antiresonance Reflection Optical Waveguide)-type structures. An embossing technique was applied to make diffractional grating couplers.     

五层MOS光波导TE模光学特性的简化分析

应用一种简化的方法对五层MOS光波导的光学特性进行了分析,给出了TE模传播常数和吸收损耗系数的近似计算公式,并结合计算结果检验了本方法及公式的精度,为实现波导中TE_0模低损耗单模传输,讨论了某些波导参量的选择.     

Rigorous Analysis of the Disk-Loaded Waveguide Slow-Wave Structures

Recently disk-loaded waveguide has been widely used in high-power traveling wave tubes (HPTWT). Although TM ₀₁ mode is it's main mode, the asymmetry mode may be excited by slight asymmetry of the structure, misalignment of the beam, or the asymmetry associated with the input or output structure. So research about asymmetry mode of disk-loaded waveguide is necessary. The general dispersion equation and interaction impedance expression of disk-loaded waveguide is obtained with accurate field theory for the first time. Based on these results, a broadband and a narrowband disk-loaded waveguides are designed which can be used in the Ka band HPTWT. Moreover, the theoretical calculated results are compared with the simulated results from the HFSS (High Frequency Structure Simulator) code using finite element method. It is found that frequency domain overlapped by these two modes of the narrowband structure is very narrow, so the HEM ₁₁ mode may be ignored when calculating Beam-wave interaction. In the other hand, the interaction impedance of HEM ₁₁ mode is very low generally.     

一种用单模光纤制作亚微米周期光栅的方法

本文报道一种用单模光纤制作亚微米周期光栅的全息方法,并详细分析和讨论了影响光栅质量的各种因素。实践证明这一方法完全适于制作面积不小于10×10mm~2适于集成光学元件需要的高质量光栅。