基于光子带隙结构的微波谐振腔的分析与设计

发布时间：2018-03-10 13:05

本文选题：光子带隙　切入点：模式竞争　出处：《华北电力大学》2015年硕士论文　论文类型：学位论文

【摘要】：在毫米、亚毫米及太赫兹波段的注-波相互作用回旋器件中,采用基模工作的回旋管由于尺寸小加工困难和热损耗高,往往需要采用过模结构,然而随之带来了更加严重的模式竞争,光子晶体的出现无疑是解决这一问题的有效途径。本文在计算了光子晶体结构的能带特征和全局带隙图的基础上,针对光子晶体回旋管的Q值较高和模式洁净等问题进行了深入研究,分析总结了一套比较完善对特定频率的光子晶体回旋管的优化设计方案。首先,针对光子晶体谐振腔Q值较高的问题,分别采用加载介质柱的混合结构和介质微扰两种方法对其进行有效的控制,并分析了两种方法对光子晶体谐振腔模式选择性的影响。结果表明,两种方法都能在不改变谐振腔的频率选择性和场分布的基础上有效降低Q值,而介质微扰的方法还同时清除了与TE04模竞争的两种杂模,提高了模式选择性。然后,针对PBG谐振腔中仍存在模式竞争且晶格尺寸仍然较小的问题,以TE04模为例,通过对工作点的位置和电子注入参数的优化设计,将TE04模光子晶体谐振腔中的竞争模式全部清除,使谐振腔在整个工作频段达到单模工作,并且增加了晶格常数和金属柱半径,使之能够承受更大的热损耗,有助于提高谐振腔的功率容量。最后,通过进一步研究TE模式的全局带隙图和模式分布特点,发现在高阶带隙内,光子晶体结构虽然能抑制竞争模式,但谐振腔未达到单模工作状态。通过对光子晶体回旋管的电子注参数进行注-波非线性理论的数值模拟研究,使270GHz三次谐波类TE15模回旋管达到单模运行,有效的抑制了模式竞争。理论上的获得了43kW的输出功率和约为14.3%的注-波互作用效率。
[Abstract]:In millimeter, submillimeter and terahertz waveband beam-wave interaction gyrotron, the gyrotron operating in the base mode is often required to adopt the over-mode structure because of the difficulty of small size machining and the high heat loss. However, the emergence of photonic crystals is undoubtedly an effective way to solve this problem. In this paper, the band characteristics of photonic crystal structures and the global band gap diagram are calculated. Aiming at the problems of high Q value and mode cleanliness of photonic crystal gyrotron, a set of optimized design scheme for photonic crystal gyrotron with specific frequency is analyzed and summarized. Aiming at the problem of high Q value of photonic crystal resonator, the mixed structure of loaded dielectric column and the dielectric perturbation method are used to control it effectively. The effects of two methods on the mode selectivity of photonic crystal resonators are analyzed. The results show that both methods can effectively reduce the Q value without changing the frequency selectivity and field distribution of the resonators. The dielectric perturbation method also eliminates two kinds of heteromode competing with TE04 mode and improves mode selectivity. Then, for the problem that mode competition still exists in the PBG resonator and the lattice size is still small, the TE04 mode is taken as an example. By optimizing the position of the working point and the parameters of the electron injection, the competition mode of the TE04 mode photonic crystal resonator is eliminated, which makes the resonator work in a single mode in the whole operating frequency band, and increases the lattice constant and the radius of the metal column. It is helpful to increase the power capacity of the resonator. Finally, by studying the global bandgap diagram of te mode and the characteristics of mode distribution, it is found that in the high-order bandgap, Although the photonic crystal structure can suppress the competitive mode, the resonator does not reach the single-mode working state. The beam parameters of the photonic crystal gyrotron are numerically simulated by the beam-wave nonlinear theory. The 270GHz third-harmonic TE15 mode gyrotron is operated in a single mode, which effectively suppresses the mode competition. The output power of 43kW and the beam-wave interaction efficiency of about 14.3% are obtained theoretically.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN12

【相似文献】