中文摘要
PBG结构最大的特点是拥有光子带隙，带隙内的模不能传出结构，被约束在缺陷中，由于结构只能支持带隙内的模传输，从而提供了抑制由尾场激励的高次模的可能。本课题分别用不同的数值方法计算了金属和介质棒三角阵列PBG结构以及光子晶体光纤带隙图，分析了约束主模、抑制高次模的条件。多次研制了X波段金属PBG谐振单腔，谐振腔的Q值从800提高到3800。首次提出了把最外层的部分金属棒替换为SiC棒吸收材料，计算表明可有效引出和吸收TM11偶极模，而对TM01加速模影响较小。采用基于"三频率"法的耦合器定量设计方法，完成了PBG结构耦合器的数值模拟设计与实验研究，工作频率附近，加速模的驻波比达到了1.06。另外，PBG 加速结构具有高梯度加速的潜力，为此，进行了介质-金属混合加载的PBG微波加速结构的设计与模拟；选择了光子晶体光纤中的out-plane-wave以满足纵向电场，使用了超级晶胞的周期化近似方法对引入缺陷的光子晶体光纤结构进行了计算，优化了加速结构尺寸。推导和使用了全向量平面波展开法计算Woodpile三维光子晶体的带隙分布，给出了用FDTD方法对该种结构设计的方案。
英文摘要
The most remarkable property of PBG structure is the photonic band gap. The wave with a frequency inside the band gap cannot propagate into the bulk of the PBG structure. PBG structures were introduced to the field of accelertor because they can be used to suppress the HOM in accelerating structure. The global band gap diagrams for 2D triangular crystal lattice of metal and dielectric rods and photonic crystal fiber were calculated respectively. The metallic PBG resonator(X-band) with the Q-factor being 3800 was developed sucessfully.Half of the resonator's outer wall was removed and SiC rods were suggested firstly to be placed at the periphery in order to achieve the HOM damping. According to numerical simulations, the TM11 mode leaks out can be absorbed by absorbers effectively while the influence to TM01 mode is quite little. A quantitative method of coupler simulation which is based on the Kyhl. method was introduced to the PBG structure couplers' design. The locations of some rods between the rectangular waveguide and the center of the coupler were ajusted for tuning and matching. A 4-cell metallic travelling wave PBG accelerating structure with couplers was studied experimently. The SWR of the accelerating mode is about 1.06 near the operating frequency.We selected a metallic-dielectric PBG based cavities to establish an overmoded photonic crystal accelerating structure which consists of dielectric rods and metal disks with irises. We simulated the accelerator structures and optimized the dimensions for the operating higher-order TM02-like mode. We selected the out-plane-wave plane wave expansion method for the longitudinal electronic field confinement in photonic crystal fibers and calculated the dispersive curve versus variation of kz and speed of line for synchronization. Then super cell approximation was introduced for calculating the defected photonic crystal structure.The geometry and the dimensions of photonic crystal fiber accelerator structure was optimized and designed.The full vector plane wave expansion method to calculate the band gap of woodpile structure was used and the calculation scheme by using the FDTD method for defected structure was proposed at last.
结题摘要
PBG结构最大的特点是拥有光子带隙，带隙内的模不能传出结构，被约束在缺陷中，由于结构只能支持带隙内的模传输，从而提供了抑制由尾场激励的高次模的可能。本课题分别用不同的数值方法计算了金属和介质棒三角阵列PBG结构以及光子晶体光纤带隙图，分析了约束主模、抑制高次模的条件。多次研制了X波段金属PBG谐振单腔，谐振腔的Q值从800提高到3800。首次提出了把最外层的部分金属棒替换为SiC棒吸收材料，计算表明可有效引出和吸收TM11偶极模，而对TM01加速模影响较小。采用基于"三频率"法的耦合器定量设计方法，完成了PBG结构耦合器的数值模拟设计与实验研究，工作频率附近，加速模的驻波比达到了1.06。另外，PBG 加速结构具有高梯度加速的潜力，为此，进行了介质-金属混合加载的PBG微波加速结构的设计与模拟；选择了光子晶体光纤中的out-plane-wave以满足纵向电场，使用了超级晶胞的周期化近似方法对引入缺陷的光子晶体光纤结构进行了计算，优化了加速结构尺寸。推导和使用了全向量平面波展开法计算Woodpile三维光子晶体的带隙分布，给出了用FDTD方法对该种结构设计的方案。