Influence of Buffer-Layer Thickness on Performance of Waveguide Modulators

ＩｎｆｌｕｅｎｃｅｏｆＢｕｆｆｅｒ－ＬａｙｅｒＴｈｉｃｋｎｅｓｓｏｎＰｅｒｆｏｒｍａｎｃｅｏｆＷａｖｅｇｕｉｄｅＭｏｄｕｌａｔｏｒｓ￥ＸＡＩＮＧＹｕｎｎａｎ；ＷＡＮＧＫｕｉｒｕ；ＹＵＧｕｏｘｉａｎ；ＸＵＤａｘｉｏｎｇ（ＢｅｉｊｉｎｇＵｎｖｅｒｓｉｔｙ...     

Numerical Analysis of Gratings with Graded Refractive Index Profile Waveguides

ＮｕｍｅｒｉｃａｌＡｎａｌｙｓｉｓｏｆＧｒａｔｉｎｇｓｗｉｔｈＧｒａｄｅｄＲｅｆｒａｃｔｉｖｅＩｎｄｅｘＰｒｏｆｉｌｅＷａｖｅｇｕｉｄｅｓ￥ＣＨＥＮＣｈａｎｇｈｕａ；ＣＨＥＮＬｉａｎｇｈｕｉ；ＷＡＮＧＱｉｍｉｎｇ（ＮＩＯＥＬＩｎｓｔｉｔｕｔｅｏｆＳｅ...     

硅基GaAs／GaAlAs平面光波导的研究

分析了金属有机化合物化学气相淀积（ＭＯＣＶＤ）ＧａＡｓ／ＧａＡｓＡｌ／ＧａＡｓ／Ｓｉ材料结构的性能，用ＭＯＣＶＤ法地硅衬底上生长了ＧａＡｓ／ＧａＡｓＡｌ／ＧａＡｓ材料，并用这种材料制备了平面光波导样品，测定了１．３μｍ，单模激光的传输损耗小于０．６５ｄＢ／ｃｍ。     

非线性对称平板光波导TE模色散特性的近似计算

本文利用微扰法,导出了克尔型非线性对称平板光波导TE模传播常数的近似计算公式。结果表明,本文公式得到的结果与精确结果吻合得很好。     

Research on the Characteristic of the Disk-Loaded Waveguide, Rib-Loaded Disk-Loaded Waveguide and Helix Slow-Wave Structures

The fast development of modern electronic warfare, broadband high power array radar system, high power jammer and microwave directional power weapon imposes high demand on high power microwave resource. With such features as high power, broadband, multi-mode, etc., traveling wave tubes (TWTs) play an important role in the high power microwave amplifiers. Since the slow-wave system is the core of beam-wave interaction in TWTs, the function and performance of it directly determine the capability of the TWTs.     

高功率同轴波导Ubitron放大器的高频特性研究

 用三维非线性理论，对高功率同轴波导Ubitron放大器进行了研究。该Ubitron放大器采用环形相对论电子注与同轴波导的TE₀₁模相互作用。通过数值模拟，在Ku波段得到了2.24MW的输出功率，其效率为10.9%，带宽为35% 。数值计算结果表明：电子注的自场导致饱和功率减少，频带变窄，增益下降。使用摇摆器幅值渐变，器件工作效率从10.9%提高到12.3%。     

A novel numerical synthetic technique for determination of the TMon dispersion relation in a coaxial corrugated cylindrical waveguide

A novel, highly accurate numerical synthetic technique for determining the complete dispersive characteristics of electromagnetic modes in a spatially periodic structure is presented. The numerical method based on the coupling of the finite difference method in time domain with the discrete fourier transform is applied to calculate the eigenfrequencies and eigenfield distribution of a resonant cavity which is an appropriately shorted periodic slow wave circuit of N periods at both ends. The analytical synthetic technique, which is based on the intrinsic characteristic of spatially periodic structure, is used to derive the complete dispersion relation using the numerically measured resonances. The method was successfully applied for the case of TM_on modes in a coaxial corrugated waveguide and is applicable to slow wave structures of arbitrary geometry.     

Ohmic quality of resonators shaped by corrugated guide sections at frequencies near bragg stop bands

The effect of ohmic loss decrease in corrugated waveguide is studied for the case of period, equal to half of longitudinal wave length (so called π-type oscillations). As demonstrated, in periodical guide there are π-type waves with ohmic quality growing approximatelly as a cube of guide radius, which looks very attractive for different applications.     

同轴插板式模式转换器频率特性研究

通过分析同轴插板式模式转换器的模式耦合过程,推导了模式转换器转换效率与频率的关系式,进而研究了其频带宽度与转换器同轴波导内外径参数之间的关系.通过数值计算,给出了可获得最大带宽的模式转换器设计条件:同轴波导的内、外半径之和约为波长的0.824倍,外半径小于波长的0.525倍.     

Considerations on material composition for low-loss hollow-core integrated optical waveguides

The role of cladding bilayer material compositions to obtain low-loss hollow-core integrated optical waveguides was studied. Using the simple Fresnel reflection formulae, the optimal material composition was determined. It is shown that using bilayers with higher index-contrast does not always lead to a lower loss for (quasi-)linearly polarized modes. Based on that knowledge, structures that exhibit very low leakage loss for quasi-TE₀₀ mode are proposed and designed using Si-compatible materials.