微纳尺度光纤布拉格光栅折射率传感的理论研究

亚波长直径微纳光纤强倏逝场传输的光学特性,使其对周围介质折射率的变化具有极高的灵敏度.本文提出一种基于微纳尺度光纤布拉格光栅(MNFBG)的折射率传感器,结合微纳光纤倏逝场传输和光纤布拉格光栅(FBG)强波长选择的特性来实现高精度折射率传感,对其制备可行性进行了讨论.论文中对MNFBG折射率传感机理进行了深入的理论分析,并使用OptiGrating软件进行了数值模拟,模拟数据显示MNFBG折射率测量的灵敏度随着光纤半径的减小而增加,其中光纤半径为400 nm的MNFBG灵敏度可达到993 nm/RIU,相比于包层蚀刻的FBG灵敏度增加了170倍,说明MNFBG对发展微型化、高灵敏度折射率传感器具有良好的应用前景. 关键词： 微纳光纤 光纤布拉格光栅 折射率传感     

High-Sensitivity Sensor Based on Surface Plasmon Resonance Enhanced Lateral Optical Beam Displacements

We present a new optical sensor based on surface plasmon resonance （SPIt） enhanced lateral optical beam displacements. Compared with the traditional SPIt methods, the new method provides higher sensitivity to the sensor system. Theoretical simulations show that the refractive index （RI） detection sensitivity of the SPR sensor based on the displacement measurement has a strong dependence on the thickness of the metal film. When the optimal thickness of the metal film is selected, the RI resolutlon of the SPIt sensor is predicted to be 2.2 × 10^-7 refractive index units （RIU）. Furthermore, it is found that the incidence angle can be used as a parameter to adjust the operating range of the sensor to different refractive index ranges.     

一类系统的极限环讨论

文[1]研究了二次系统 dx/dt=-y+dx+x~2+dxy-y~2 dy/dt=x·(1+ax+y)证明了ad≤0或ad≥3时,(E_2)无围绕原点的极限环,0相似文献   

Effect of surface oxygen vacancy defects on the performance of ZnO quantum dots ultraviolet photodetector

The slower response speed is the main problem in the application of ZnO quantum dots (QDs) photodetector, which has been commonly attributed to the presence of excess oxygen vacancy defects and oxygen adsorption/desorption processes. However, the detailed mechanism is still not very clear. Herein, the properties of ZnO QDs and their photodetectors with different amounts of oxygen vacancy (V_O) defects controlled by hydrogen peroxide (H₂O₂) solution treatment have been investigated. After H₂O₂ solution treatment, V_O concentration of ZnO QDs decreased. The H₂O₂ solution-treated device has a higher photocurrent and a lower dark current. Meanwhile, with the increase in V_O concentration of ZnO QDs, the response speed of the device has been improved due to the increase of oxygen adsorption/desorption rate. More interestingly, the response speed of the device became less sensitive to temperature and oxygen concentration with the increase of V_O defects. The findings in this work clarify that the surface V_O defects of ZnO QDs could enhance the photoresponse speed, which is helpful for sensor designing.     

一类三角问题解的讨论

在高中数学课本、课外参考书及报刊杂志上 ,经常会碰到这样一类三角问题 :已知　ｃｏｓα±ｃｏｓβ =ｍ ,ｓｉｎα±ｓｉｎβ =ｎ .求 :ｓｉｎ(α±β)的值 .文 [1],[2 ]对特殊情形 :已知ｃｏｓα -ｃｏｓβ =12 ,ｓｉｎα -ｓｉｎβ =- 13,求ｓｉｎ(α + β)的解法及避免增解作了分析 ,文 [1]还提出条件不变 ,ｓｉｎ(α - β)符号怎样验证和判断的困惑 ,本文对这类问题进行分析与讨论 ,以加深对这类问题解的认识 .显然上述问题的条件有四种不同组合 :(Ⅰ ) ｃｏｓα +ｃｏｓβ =ｍ ,ｓｉｎα +ｓｉｎβ =ｎ .(Ⅱ ) ｃｏｓα -ｃｏｓβ =ｍ…     

高速线性光采样用被动锁模光纤激光器重复频率优化

线性光采样是一种测量基于先进调制码型的高速光信号的有效手段, 而被动锁模光纤激光器是其实施所需的关键组件. 本文在介绍线性光采样工作原理的基础上, 首次分析得到被动锁模光纤激光器重复频率与待测信号光线宽的约束关系, 对于正交相移键控(QPSK)信号, 当信号光线宽与采样光脉冲重复频率的比值小于1.5×10^-3 时, 高速信号的相位噪声对线性光采样带来的损伤可以忽略不计. 利用95.984 MHz重复频率的被动锁模光纤激光器对线宽为100 kHz速率为28 Gbaud的QPSK信号开展相关实验, 通过标准数字相干接收算法可以得到与传统高速示波器相同的星座图, 理论分析与实验结果完全符合. 这一研究结果有助于线性光采样用被动锁模光纤激光器的优化设计.     

1.3μm光学环行器正向损耗及反向隔离比的理论及实验研究

在理论及实验上分析了影响光环行器插入损耗及反向隔离比的因素,讨论了环行器中起、检偏镜参数对其性能的影响.结果表明,起、检偏镜的各组参数存在最佳选择,以保证环行器具有低插损、高隔离比及与偏振无关的特性.作者研制的环行器正向损耗小于1dB,反向隔离比在25.5dB与28dB之间.     

辐射输运方程的Monte Carlo解法

In this paper a Monte Carlo Method which used to solve the time-dependent equation of nonlinear radiation transport is given and the equivalence of the solution to that of the time-dependent equation of linear transport is also proved.     

偶然与必然——进行德育的好材料

在科学发展史上,尤其在化学发展史上,有很多发明与发现往往起因于偶然因素。世界炸药大王,诺贝尔奖金创立者诺贝尔发明黄色炸药就是一例。在黄色炸药发明之前,诺贝尔经过千百次反复实验制出了一种叫硝化甘油的液体炸药,一晃就爆炸,很危险。为了安全起见,在运输时就把它装在铁盒里,铁盒之间填充一种叫硅藻土的白色粉末,使硝化甘油不至于晃荡。     

用于光纤拉曼放大器抽运源的单级光纤拉曼激光器

抽运光源是光纤拉曼放大器应用于密集波分复用系统的关键技术,设计了一种紧凑型的808nm激光二极管抽运的基于钒酸钇（Nd^3＋：YVO4）晶体1342nm固体激光器模块,提出利用上述1342nm固体激光器抽运基于光纤光栅的单级全光纤型拉曼谐振器获得1．4μm激光输出的光纤拉曼激光器,分析了固体激光器的阈值特性、性能优化方法和单级光纤拉曼谐振器的设计方法。上述1342nm固体激光器模块在抽运功率2W时获得了最大655mW的激光输出功率和42．6％的斜率效率,单级拉曼谐振器的1342nm到1．4μm光功率转换斜率效率达75％,在1425nm、1438nm、1455nm和1490nm处的输出功率达到300mW以上。最后给出基于1．4μm光纤拉曼激光器抽运的宽带平坦放大的光纤拉曼放大器的结构参量和性能测试结果。