Structure Dependence of Mode Edges in Photonic Crystal Waveguide with Silicon on Insulator

The mode edges of photonic crystal waveguide with triangular lattice based on a silicon-on-insulator slab are investigated by combination of the effective index method and the two-dimensional plane wave expansion method. The variations of waveguide-mode edges with the structure parameters of photonic crystal are deduced. When the ratio of the radius of air holes to the lattice constant, r/ ∧, is fixed and the lattice constant of photonic crystal, A, increases, the waveguide-mode edges shift to longer wavelengths. When A is fixed and r/∧ increases, the waveguide-mode edges shift to shorter wavelengths. Additionally, when r/∧ and A are both fixed, the radius of the two-row air holes adjacent to the waveguide increases, the waveguide-mode edges shift to shorter wavelengths.     

原位红外光谱技术研究HMX炸药热分解

原位红外光谱法是近十几年来新兴的一种动态研究方法。该方法结合了原位实时监控和红外光谱精确分析物质化学结构的优点，通过实时跟踪材料在不同温度下的化学变化，测定材料的微观结构与温度的关系。本实验采用原位红外光谱技术研究了HMX炸药在5℃／min升温条件下的热分解过程，得到如下结论。     

大粘度复合纳米材料面投影微立体光刻系统的分辨率研究

 基于数字微反射镜的动态掩膜面投影微立体光刻技术是一种基于快速原型制造思想的新型微细结构加工手段,其系统中常用树脂槽和涂覆装置使得其无法适用于粘度大的固化材料。为实现粘度大的复合纳米材料的固化制造,构建了新型的基于数字微反射镜技术的动态掩膜微立体光刻系统,该系统的加工横向分辨率由系统的光学分辨率与树脂特性共同决定。当单层树脂固化厚度超过临界值时,系统的横向分辨率将降低。根据实验中测量光学系统的分辨率以及树脂的工作曲线,得到本系统的最高横向分辨率可以达到14 μm。     

微小型航天密封圈表面缺陷检测

微小型航天密封圈表面缺陷面积占比小,目前的检测方法检测效率低、结果不稳定,检测速度和检测精度仍有提升空间。针对上述问题,提出两种基于深度学习的密封圈表面缺陷检测算法。在MobileNetv2的反向残差模块中加入多头注意力机制,构建出轻量级主干网络Efficient Model;使用Next Hybrid策略,融合工业级Transformer网络中的多个注意力机制模块,构建出Next Generation Vision Transformer主干网络。在上述两种主干网络中分别加入特征提取网络,设计出Efficient-FPN Model和Transformer-FPN Model检测算法。实验结果表明,Efficient-FPN Model和Transformer-FPN Model检测算法的平均准确率均高于YOLOv5s、YOLOv5x以及YOLOv5z,其中,Transformer-FPN Model模型的平均准确率最高,达到91.4%。Efficient-FPN Model的检测速度在五种模型中最快,达到110.8 frame/s,其平均准确率达到86.1%,也高于其他YOLOv5...     

"函"与"f"的对话

F:喂,老"函"!您今天匆匆忙忙忙什么? 　　函:<九头鸟茶楼>今天开业,我送"清新解困"茶. 　　F:那好,我们俩一起去!你的全名不是叫"函数"吗?怎么现在只称"函"呢?……     

六十甲子说中华

在新中国六十华诞前夕,九头鸟茶楼挂出了一幅新联. 　　上联是:二五天为干 　　横联是:六十甲子 　　下联是:三四地作支 　　九头鸟茶楼上有壁挂,按中华传统文化解释了这幅对联的数学内涵.……     

戏说数学家

九头鸟茶楼今天有故事会,门外挂出了一副新联. 左联是:主题一个专家只因专注 右联是:故事三则笑话到底笑谁 横批是:人在戏中.     

与高一新生讲"映射"

"映射"并不玄,与我常相伴, 　　顾名可思义,对镜解疑难! 　　上四句,是高一新生小何在新课本"映射"概念旁边写的一段感悟.……     

基于螺旋相位调制的非相干全息点扩散函数研究

分析了菲涅耳非相干相关全息(Fresnel incoherent correlation holography,FINCH)系统中纯相位空间光调制器(spatial light modulator,SLM)加载螺旋相位掩模时的点扩散函数.以氙灯为照明光源搭建了FINCH系统,电荷耦合器记录的点源全息图与点扩散函数模拟结果一致.采用该系统分别在SLM上加载双透镜掩模和螺旋相位调制双透镜掩模两种情况下对分辨率板和非染色洋葱细胞成像,给出了成像对比结果.结果表明:采用螺旋相位调制的FINCH系统可以在几乎不牺牲分辨率的情况下提高图像的边缘对比度;同样,对相位物体也可以实现图像的边缘提取和识别.该方法在实时监测活细胞的分裂、形变等方面具有重要应用前景.     

A ministop band in a single-defect photonic crystal waveguide based on silicon on insulator

This paper reports that a two-dimensional single-defect photonic crystal waveguide in the \textit{$\Ga$-K} direction with triangular lattice on a silicon-on-insulator substrate is fabricated by the combination of electron beam lithography and inductively coupled plasma etching. A ministop band (MSB) is observed by the measurement of transmission characteristics. It results from the coupling between the two modes with the same symmetry, which is analysed from the stimulated band diagram by the effective index and the two-dimensional plane wave expansion methods. The parameter working on the MSB is the ratio of the radius of air holes to the lattice constant, $r/a$. It is obtained that the critical $r/a$ value determining the occurrence or disappearance of MSB is 0.36. When $r/a $ is larger than or equal to 0.36, the MSB occurs. However, when $r/a $ is smaller than 0.36, the MSB disappears.