利用转移矩阵法和频域块迭代法分析点缺陷二维光子晶体

本文介绍了广泛用于分析光子晶体的两种方法；转移矩阵法和频域块迭代法。运用这两种方法，我们研究了一个5行5列在空气中呈正方排列的二维介质柱晶体，改变中心介质柱的半律和介电常数，分别得到各自对应不同的透射和色散关系曲线，对于同一参数结构的光子晶体，不同算法得到的带隙和缺陷态频率是一致的。同时根据透射和色散曲线所体现出来的晶体特性，我们分析了将光子晶体用作激光谐振腔以提高Q值的机理。     

Predicting different losses of photonic crystal fibers in material and hetero-core domain

In order to develop the effective transmission in photonic crystal fiber (PCF), the (realizable fiber i.e.,) losses arising from bending as well as splicing are very vital issues. We report here macrobending loss of PCFs in different material composites. Further, we make comprehensive numerical analysis related to splice loss issues arising from joining PCF with PCF and single mode fiber as well. We additionally investigate dependence of all these losses with respect to structural parameters of PCF. Hetero core systems are found to yield lower losses as compared to their identical counterpart. The numerical estimates reported here will provide a base for engineering effective communication guides in the context of material and hybrid core domain.     

新型基于PBG结构的宽带高增益贴片天线及阵列技术研究

设计了一种新型基于哑铃型光子带隙(PBG)的宽带高增益E形贴片天线.实现X波段天线单元38.2%的阻抗带宽(VSWR＜2)且频带内增益提高1-2.5 dB.将PBG结构应用于天线阵列,实现了全频带增益的提高,且单元端口互耦隔离度最大可提高5 dB.仿真和实测结果有好的一致性.     

SnO2反opal光子晶体的制备及表征

以PS opal膜为模板制得了SnO2反opal光子晶体膜。采用浸渍提拉法和Sol-LPD法对PS opal模板进行填充,450℃焙烧除去PS模板得到SnO2反opal光子晶体。SEM和UV-Vis透射表征显示,两种填充方式都能得到三维有序的SnO2反opal光子晶体;以相同的PS opal膜为模板,通过Sol-LPD填充法得到的SnO2反opal膜的禁带位置向长波移动(以浸渍提拉法制得的光子晶体的禁带位置为基准)。这证实Sol-LPD填充法比浸渍提拉法有更高的填充率。通过Sol-LPD填充法还能够制备具有多重禁带的SnO2反opal异质复合膜。     

Self-X Materials and Structures in Nature and Technology: Bio-inspiration as a Driving Force for Technical Innovation

Over the course of 3.8 billion years of biological evolution, nature has found the answers to many engineering problems. The aim of biomimetics is to analyse and tap biology's potential as a huge reservoir for innovative solutions. Thomas Speck , Professor and Director of the Plant Biomechanics Group (PBG) at the University of Freiburg and the Freiburg Centre for Interactive Materials and Bioinspired Technologies (FIT), Jan Knippers , Professor and Head of the Institute of Building Structures and Structural Design (ITKE) at the University of Stuttgart, and Olga Speck , a researcher at the PBG, scientific coordinator of FIT and manager of the Competence Network Biomimetics at Freiburg, explain how biological material systems with self-x properties are cost-efficient, multifunctional, and can be environmentally friendly; and with several billion trial runs, have surely stood the test of time.     

Design and analysis of planar printed microwave and PBG filters using an FDTD method

In this paper, various planar printed microwave and photonic band-gap (PBG) filters have been designed and analyzed by applying the finite difference time domain method, together with an unsplit-anisotropic perfectly matched layer technique as treatments of boundary conditions. The implemented solver was first validated by comparing the computed data with those published in literature, and a good agreement was observed between the results. Then, based on the specified design criteria, various microwave and PBG filters were designed and analyzed, in which the theoretical predictions matched well with the computed results for the characteristics of the proposed filters.     

非Yee网格的FDTD法分析复杂媒质PBG结构的带阻特性

采用电、磁场各分量均位于网格中心的高阶时域有限差分法计算PBG结构的色散特性。对简单媒质问题的计算结果与采用Yee网格时域有限差分法所得一致，但更适合于分析含复杂媒质的问题。计算了三类磁各向异性PBG结构的色散特性曲线，指出：磁各向异性媒质都可明显增宽第一阻带；对称型磁各向异性还增多色散特性曲线中的阻带数，但旋磁型各向异性则不影响阻带数。