在高功率激光二极管阵列(LDA)侧面抽运模块研究中,高效率高质量的抽运耦合结构设计非常重要。为了对抽运耦合结构进行优化设计,需要对棒状增益介质内的抽运储能分布实现量化评价。由于用于激光谐振腔和放大光路的激光二极管抽运模块的抽运储能分布要求不同,因此对激光振荡模块和放大模块中的抽运储能分布分别建立了一套评价方法。分别对激光振荡模块和放大模块中的抽运储能分布进行实例评价分析,结果表明,所提出的评价指标和计算方法既能充分反映出放大模块中抽运储能分布的储能沉积效率和抽运均匀性变化情况,也能反映出激光振荡模块中抽运储能分布与谐振腔模分布的匹配程度。

An asymmetric Jerusalem unit and the frequency selective surface (FSS) structure composed of such units are designed. The transmittance of the designed FSS structure is calculated by mode-matching method and compared with the test results. The comparison results show that the FSS center frequency of the asymmetric structure unit drifts little with the variation of the incident angles of the electromagnetic waves and keeps relatively stable. The research offers a new choice for the application of FSS under the large scanning angle of electromagnetic waves.

We review some of the recent advances in the development of subwavelength plasmonic devices for manipulating light at the nanoscale, drawing examples from our own work in metal-dielectric-metal (MDM) plasmonic waveguide devices. We introduce bends, splitters, and mode converters for MDM waveguides with no additional loss. We also demonstrate that optical gain provides a mechanism for on/off switching in MDM plasmonic waveguides. Highly efficient compact couplers between dielectric waveguides and MDM waveguides are also introduced.

Frequency-selective surface (FSS) is a two-dimensional periodic structure consisting of a dielectric substrate and the metal units (or apertures) arranged periodically on it. When manufacturing the substrate, its thickness and dielectric constant suffer process tolerances. This may induce the center frequency of the FSS to shift, and consequently influence its characteristics. In this paper, a bandpass FSS structure is designed. The units are the Jerusalem crosses arranged squarely. The mode-matching technique is used for simulation. The influence of the tolerances of the substrate’s thickness and dielectric constant on the center frequency is analyzed. Results show that the tolerances of thickness and dielectric constant have different influences on the center frequency of the FSS. It is necessary to ensure the process tolerance of the dielectric constant in the design and manufacturing of the substrate in order to stabilize the center frequency.

提出了一种新型介质栅波导阻带滤波结构,并采用多模网络与严格模匹配相结合的方法对该阻带滤波特性进行了仔细分析,给出了主模TM模的Brillouin图及滤波结构的归一化中心频率、阻带的宽度和带内最大衰减等特性和结构参数的关系.与传统的介质栅滤波器相比,新滤波器结构不仅具有金属损耗小的优点,而且其阻带带宽和带内衰减都要比传统介质栅滤波器的大得多.文中所给出的计算结果对设计该新型带阻滤波结构有指导意义.

应用模匹配理论推导和建立了单级突变的矩阵方程,并分析给出了具有多级突变和渐变结构级联情况下波导腔体的处理方法.在理论推导的基础上,通过编制程序计算出多级突变结构波导腔体模匹配系数级联矩阵,并由矩阵参数得到所需的腔体谐振频率和Q值等物理特性参量.实际计算结果表明,由程序模拟输入腔计算得到的数据结果与腔体的冷测实验结果基本一致,为进一步的注波互作用研究和回旋速调管的设计工作提供了参考依据.

设计了十字单元的远红外带通型频率选择表面(FSS),并采用模匹配法对其传输特性进行了研究,其中单元中的场分布用有限元法求出.根据此方法研究了不同极化方式的电磁波在斜入射条件下,对不同布阵方式的远红外FSS传输特性的影响.结果发现,无论单元是按正方形布阵还是按正三角形布阵,在电磁波斜入射时中心频率都随入射角的增大而向低频漂移,带宽都相应减小.但无论入射波是什么极化方式,所设计单元按正三角形布阵时的传输特性都比正方形布阵方式稳定.

在高功率微波天线系统中,要求馈源具有高功率容量和良好的辐射特性,内壁光滑的变张角结构多模馈源能够满足这一要求.在单级模匹配理论的基础上,给出了多个突变结构级联S参数矩阵的实现方法,并编制了数值计算程序.运用程序分析了各种不同结构光壁喇叭馈源,得到了其中各个模式之间的耦合关系及其口面辐射特性的变化.在大量计算的基础上,得到了φ400 mm口面直径的高功率高效率多模馈源设计方案,理论功率容量大于1.5 GW,同时具有良好的轴对称辐射特性.实验与理论分析结果具有良好的一致性.

用严格模匹配与多模网络理论相结合的方法,对几种周期介质结构的传输特性进行了深入的分析.包括两种有限长周期介质镜像波导滤波器;一种有限长变周期无辐射介质波导滤波器;一种无限长周期部分介质填充的矩形波导.实验结果表明该方法是精确有效的.

采用多模网络与严格模匹配相结合的方法,对开放型手征介质圆波导中的二种阶梯不连续性的散射和辐射特性进行分析和求解,仔细讨论了手征参数和几何尺寸对散射和辐射特性的影响.给出的结果对手征介质元器件的研究有实际的参考意义.