共查询到20条相似文献,搜索用时 22 毫秒
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单偏振单模微结构聚合物光纤理论设计 总被引:1,自引:0,他引:1
采用全矢量有限元法并结合完美匹配边界条件,得到了一种新型结构的单偏振单模微结构光纤,以聚合物聚甲基丙烯酸甲酯为基材,对其偏振模场、快轴模和慢轴模截至波长和约束损耗进行了研究.结果发现,通过改变光纤结构参量,可以使光纤基模两个正交偏振态截止波长不同,光纤中只能传输基模的一个偏振态(慢轴模).若调整光纤单偏振单模工作区在聚合物光纤通信窗口650 nm附近,该光纤传输慢轴模的约束损耗低于0.05 dB/m. 相似文献
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环境污染气体监测是防治大气污染的前提条件。污染气体的监测方法中,光谱分析方法具有原理和结构简单、响应速度快、精度高等优点。差分吸收光谱法利用气体分子在紫外-可见光谱范围的特征吸收来测量其浓度含量,是环境气体监测领域的典型光谱分析方法。根据差分吸收光谱的测量原理,提出光纤收发一体测量结构,将该结构应用于空气质量监测中。氙灯光源经耦合透镜耦合后进入入射光纤,经望远镜系统准直后出射,经过被测气体之后,由位于被测气体另一端的角锥棱镜反射后沿原路返回,再次经过望远系统汇聚,携带被测气体的信息经出射光纤传入光谱仪。根据该方法研制了样机,采用SO2,NO2标准气体对样机进行标定,并应用样机对大气中的污染气体进行现场监测。实验结果表明,该方法能够满足空气质量监测要求。 相似文献
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The formulae of photon angular distribution and polarization degree for radiative recombination are presented to include the contribution of multipoles and their correlations. A fully relativistic code is then developed to calculate the photon angular distribution and polarization. The calculated polarization degree and differential cross-sections agree well with that of Scofild's results within 10%. The effects of multipoles on polarization and angular distribution are investigated. The polarization and the angular distribution become asymmetric when the multipoles are accounted as the electron energy increases. 相似文献
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A new measurement of the differential cross section for neutron-proton scattering was performed at a neutron energy of 14.1
MeV. The neutrons were scattered from a polyethylene foil and the associated recoil protons were observed. Data were taken
at 6 angles between 89.7° and 155.7° in the centre-of-mass system. Extensive Monte-Carlo simulations were performed in order
to optimize the experimental setup and to reduce the influence of systematical errors. The data were normalized to the well-known
neutron-proton total cross section. The overall uncertainty is about ±2%. The data are in excellent agreement with the prediction
of the multi-energy phase shift analysis SM94 of Arndt and coworkers.
Received December 21, 1995; revised November 20, 1996; accepted for publication December 23, 1996 相似文献
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研究复杂目标的几何建模、光学面元消隐和目标表面的光学散射特性.针对任意构型的目标,提出采用均匀光照明仿真图像进行光学散射截面(OCS)数值计算方法.通过自适应Z缓存方法,实现目标光学消隐面的计算,将这部分消隐面面积从目标OCS的数值积分中去除.研究近似镜面材料的空间模板褶皱表面的光学散射数值模拟方法,以及基于激光主动探测系统实验测量数据的目标OCS实验分析方法.根据某缩比例空间目标相对探测系统不同方位、俯仰角情况的OCS实验结果,校正OCS数值仿真参数.仿真结果与实验结果的图像比较和OCS曲线趋势大略一致,考虑到表面褶皱的随机性、姿态的测量误差和仿真模型有限的校准能力等因素,本文提出的数值仿真方法能够在一定程度上描述目标的OCS值. 相似文献
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光纤中基于交叉相位调制的超短光脉冲串的产生 总被引:3,自引:1,他引:3
提出一种在单模光纤正常色散区由连续波产生超短光脉冲串的新方法,即让连续波和一个波长位于光纤正常色散区的调制脉冲串在光纤中同时传输,交叉相位调制效应和群速度色散效应的相互作用能使连续波演化成一串超短光脉冲,其脉冲宽度比调制脉冲串中的脉宽要小得多,本文还通过计算机模拟,对这一方法进行了全面的考察和分析。结果表明,该方法不仅实用,而且可取得较好的效果。 相似文献
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类明孤子在光纤中传输特性的变分研究 总被引:6,自引:4,他引:6
应用变分法,研究了微扰对类明孤子在光纤巾非线性传输特性的影响,导出了类明孤子脉冲参量演化的动力学方程。它统一了在单模光纤、色散缓变光纤或色散控制光纤中类明孤子脉冲参量演化的动力学方程。在此基础上,计算了色散缓变光纤中的线性高阶色散微扰。结果表明:线性高阶色散对类明孤子脉冲的位置和相位有影响,而对振幅、宽度和啁啾没有影响;光纤色散缓变对类明孤子脉冲的所有参量均有影响。 相似文献
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介绍了微分散射截面测量过程中的气压效应 ,通过深入分析得出了二次散射系数E(θ)与零度角的强度A0 成正比 ,随散射角θ的增加而增加以及它的值可正可负 .通过与实验的对比 ,证实了前两条结论 ,并指出可把该结论用于指导实验. The pressure effect for the measurement of differential cross section is introduced and analysed in detail. Three conclusions are obtained: the double scattered coefficient E(θ) is proportional to the strength A 0 of the excitations measured at 0°; E(θ) increases with the increasing of scattered angle; the values of E(θ) can be positive or negative. The front two conclusions are tested by experiment, and it is pointed that they are helpful to the measurement of differential cross section. 相似文献
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Roddy E. Ramos-Gonzáles Enver Fernandez-Chillcce Luiz C. Barbosa Hugo E. Hernández-Figueroa 《Fiber and Integrated Optics》2013,32(3):186-195
Abstract An efficient technique to control the zero-dispersion wavelength of a microstructured optical fiber is proposed and numerically demonstrated in this article. This technique is based on the variation of the linear refractive index and the thickness of a thin film covering the microstructured optical fiber holes' inner surfaces. A powerful and accurate code based on a full-vector finite-element method formulation in conjunction with perfectly matched layers was used. A maximum of 570-nm zero-dispersion wavelength displacement is demonstrated. This thin film can be included after the microstructured optical fiber has been fabricated, as that means the zero dispersion of such fiber can be tailored as needed. 相似文献
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In the review paper of N. J. Fish[1], the topics concerning the basic theory of lower hybrid wave heating and current drive are presented. Brambilla's spectrum determines the injecting wave resonance regime and its power distribution. The theories and experiments have demonstrated that the LH waves interact efficiently with the high energy electrons in the tail of their distribution in velocity space. LHCD has been used in many devices such as JET, JT-60U, and ASDEX, 相似文献