光子晶体类曲折波导慢波电路研究

【作者】 邓明金；

【导师】 宫玉彬；

【作者基本信息】 电子科技大学 ， 物理电子学， 2008， 硕士

【摘要】 自20世纪80年代光子晶体诞生以来,光子晶体的研究已经成为全世界关注的热点课题,关于光子晶体的应用研究更是精彩纷呈。光子晶体是一种电磁特性周期性变化的特殊材料,其根本特性是具有光子带隙(PBG)。由于无法使用完全自动化的工艺实现加工,行波管(TWT)的成本一直居高不下,并且一致性和可靠性差。此外,工作频率提高后,由于尺寸共渡效应,传统行波管慢波系统遇到了尺寸小、功率容量低等困难。光子晶体的出现为实现行波管的自动化加工和一致性生产,以及突破现有的频率上限带来了新的希望。本论文将光子晶体应用于行波管慢波结构,用光子晶体取代传统行波管慢波结构的金属屏蔽外壳。由于光子晶体同时具有全反射电磁波和滤波的功能,将适当光子晶体应用于慢波结构可以只将工作模式束缚在慢波结构中,而使非工作模式向外辐射。这样,相较于金属封闭的慢波电路,其中能存在的模式数量就大为减少,因此行波管的稳定性有望提高。本论文首先对光子晶体的计算方法进行了比较,以无限二维光子晶体为例,通过平面波展开法,推导了E极化和H极化波的本征方程,讨论了超晶格等效的方法。其次,由于解析方法的使用范围有限,本论文介绍了利用电磁仿真软件CSTMWS分析光子晶体带结构的方法,并针对二维正三角格子金属圆柱光子晶体进行了研究,计算了相应光子晶体的带结构,讨论了光子晶体结构参量对带结构的影响。最后,本论文讨论了光子晶体行波管的工作原理,提出了光子晶体类曲折波导慢波结构,讨论了光子晶体类曲折波导慢波结构的设计方法。研究了利用E极化波第一禁带以及第二禁带工作的光子晶体类曲折波导慢波结构。针对利用E极化波第一禁带工作的光子晶体类曲折波导慢波结构,讨论了结构参量对此类慢波结构的色散及耦合阻抗的影响。本论文的研究可为光子晶体慢波电路的研究提供一定的参考。更多还原

【Abstract】 The research on photonic crystals has become a hot topic in the world since the concept of photonic crystals has been proposed in the 1980s, and the application research of the photonic crystals is brilliant and fruitful. Photonic crystals are a kind of novel artificial material with special electromagnetic response characteristics. The basic characteristic is photonic band gap (PBG).Because can’t be machined automatically, the cost of traveling wave tubes (TWTs) is very high, and the products are not completely consistent, so does the reliability. Further more, the transit of electrons becomes more difficult in TWTs when operating frequency is high. High cost and problem of electron transit extensively limit the application range and the development of TWTs. The solutions of electron transit inside high frequency band only base on new mechanism of electromagnetic wave propagation. Photonic crystals bring new possibility of decreasing cost, resolving problem of electron transit and improving products consistent.The theme of this dissertation is photonic crystal slow-wave structure. Photonic crystals have the capability of reflecting and filtering the electromagnetic waves. If photonic crystal slow-wave structure is designed properly, the desired modes can be bounded in the slow-wave structure, while the undesired modes can radiate out of the slow-wave structure. In comparison with the slow-wave structure enveloped by metal, the modes in the photonic slow-wave structure are greatly reduced and the stability of the traveling-wave tube can be increased.In this dissertation, firstly, the background of research and present applications of photonic crystals is briefly introduced; the significance and the researching scope of this dissertation are presented first. Based on plane wave expansion method, the intrinsic equations of E mode and H mode of infinite two dimensional photonic crystals are deduced.Secondly, Because of the limitation of analytical methods, a new photonic crystal band gap simulation method using the high frequency simulation software CST MWS is introduced. Then, the high frequency simulation software CST-MWS is applied to analyze the crystal band gaps and the influence of structure parameters on the band gaps. Considered that the entire actual devices are finite, the modes of finite metallic photonic crystals are discussed.Finally, the basic principle of photonic crystal slow-wave structure is discussed and the photonic crystal folded waveguide slow-wave structure is put forward. Then, the photonic crystal folded wave guide slow-wave structure using the first photonic crystal band gap of E mode is investigated, and the effects of structure parameters on the dispersion characteristic and interaction impedance are analyzed. The photonic crystal folded waveguide slow-wave structure using the second photonic crystal band gap of E mode is also investigated. Paper presented here can provide a reference for the study of photonic crystal slow-wave structure.更多还原