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基于矢量模型,从麦克斯韦方程组出发精确计算了空芯光纤中HE_(11)模的电磁场分布,并分析了电磁场各分量的传播特性。研究表明,HE_(11)模强度沿光纤横截面呈环状分布,电场分量E_r和E_φ相位相同,磁场分量H_r和H_φ相位相反。以~(85)Rb原子为例,当入射激光功率为1 W,失谐量为1 GHz,空芯光纤空心区半径为0.7mm时,计算了空芯光纤中HE_(11)模的绝对强度分布和光学势分布,计算发现空心区最大光学势为14.9 mK,远大于标准磁光阱中~(85)Rb原子温度(120mK),因此空芯光纤中的HE_(11)模可用于导引~(85)Rb原子。空芯光纤原子导引有望应用于原子干涉领域。 相似文献
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基于麦克斯韦矢量模型精确计算了空心光纤中HE_(11)模的电磁场分布,从光源参数和光纤参数两方面讨论了HE_(11)模在空心光纤中的传播特性。研究表明:沿空心光纤截面HE_(11)模的光场强度呈环状分布,电场的两个径向分量rE和Ej相位相同,磁场的两个径向分量rH和Hj相位相反,不同光源条件在空心区激发的消逝波场分布基本一致,在纤芯层和敷层的电磁场分布随光源不同具有明显区别。此外研究表明仅改变芯层厚度或纤芯层和敷层相对折射率的方法,对空心区消逝波的电磁场分布基本没有影响,但是改变空心区半径可以明显改变空心区消逝波最大场振幅。空心光纤消逝波原子导引方法可用于原子干涉陀螺实现原子团劈裂。 相似文献
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在光纤陀螺中,由于保偏光纤的性能易受环境的影响,制约了光纤陀螺稳定性和精度的进一步提高。保偏光子晶体光纤的研究为光纤陀螺解决环境适应性问题提供了新思路,针对保偏光子晶体光纤与传统光纤的模场匹配问题,采用有限元方法,对保偏光子晶体光纤的保偏性能和模场分布特性进行了分析与研究。通过分析不同空气孔尺寸对保偏光子晶体光纤性能的影响,得到其保偏性能与模场分布特性存在相互制约性。提出了一种改善保偏光子晶体光纤模场分布的方法,并通过仿真分析验证了这一方法的可行性,这为光纤陀螺用光子晶体光纤的发展提供了借鉴。 相似文献
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针对原子干涉重力仪野外测量需求,提出一种基于单激光器系统倍频方法的高稳定、小型化激光系统方案。首先,分析了冷原子重力仪激光倍频原理;然后,以单台1560.4 nm光纤外腔激光器作为光源,基于激光倍频技术,设计了用于87Rb原子干涉重力仪的高稳定、小型化激光系统方案;最后,测试了用于重力测量的两路激光输出光束的功率稳定性。实验结果表明当780.2 nm激光输出功率为1.1 W和1.9 W时,对应功率均方根起伏分别为0.13%@4 h和0.15%@4 h,两路均可输出功率稳定、模式优良的780.2 nm激光,该系统可实现T=70 ms干涉测量,对应噪声灵敏度为610μGal/Hz。使用倍频方法的单激光器系统,实现了传统双激光器系统功能,具有高稳定、小型化特点,为原子干涉重力仪野外测量提供了技术基础。 相似文献
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《中国惯性技术学报》2021,(4)
谐振式光纤陀螺中光纤谐振腔为关键敏感器件,新型空芯光子晶体光纤具有高环境适应性和小弯曲半径等特性,有利于陀螺降低寄生噪声及小型化。针对传统熔接耦合损耗大问题,提出了基于球透镜的空间耦合谐振腔方案,分析了该谐振腔方案精度的影响因素,并给出腔内光纤耦合效率要求。根据矩阵光学理论和高斯光束传输特性推导了系统传输矩阵,并基于模场匹配法给出了系统耦合效率模型。根据导航级陀螺腔内光纤耦合效率高于87%的要求,将系统装配误差分解,完成了系统参数对装配容差的影响分析以及系统参数设计、优化及装调建议。空芯光子晶体光纤耦合误差验证实验表明,参数设计优化前后耦合效率接近,优化使得光纤径向和倾斜容差提高了约16%和100%,从而降低了装配难度,提高了系统稳定性。理论分析与实验验证基本吻合,为其工程化应用奠定了基础。 相似文献
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《中国惯性技术学报》2019,(3)
为了解决光子晶体光纤陀螺中高阶模致非互易性问题,设计了一种用于高精度光纤陀螺的单模保偏光子晶体光纤。为获得光纤结构参数最优区域,基于全矢量有限元方法开展了光子晶体光纤模场分布、双折射特性和限制损耗与三个重要结构参数(归一化频率、空气填充比、大孔直径)的依赖关系数值仿真分析。以传统熊猫型保偏光纤特性为参照,确定了光子晶体光纤结构参数最优区域。采用优化的光子晶体光纤绕制了1500 m环圈并装配于陀螺,对陀螺进行了相应测试。未采用温度补偿措施下,陀螺全温零偏稳定性优于0.008 (°)/h (100 s, 1σ),表明这种光子晶体光纤适用于高精度光纤陀螺。 相似文献
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空心光纤网络埋入复合材料中性能影响的研究 总被引:4,自引:0,他引:4
空心光纤网络可用来进行复合材料力学性能的监测,同时又可对材料的损伤进行自修复。空心光纤网络与复合材料性能的影响主要有三方面:1)复合材料对空心光纤的影响;2)空心光纤对复合材料的影响;3)空心光纤与复合材料力学性能的匹配。本文测试了三种规格的空心光纤埋入复合材料中受到的影响,依据国家有关的复合材料测试标准,对树脂基复合材料埋与不埋大直径空心光纤进行了对比实验,并论证了光纤与材料力学性能匹配点存在的必然性。从而为空心光纤网络用于复合材料的自诊断与自修复提供了研究的依据。 相似文献
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A numerical analysis has been performed for three‐dimensional developing turbulent flow in a 180° bend tube with straight inlet and outlet section used by an algebraic Reynolds stress model. To our knowledge, numerical investigations, which show the detailed comparison between calculated results and experimental data including distributions of Reynolds stresses, are few and far between. From this point of view, an algebraic Reynolds stress model in conjunction with boundary‐fitted co‐ordinate system is applied to a 180° bend tube in order to predict the anisotropic turbulent structure precisely. Calculated results are compared with the experimental data including distributions of Reynolds stresses. As a result of this analysis, it has been found that the calculated results show a comparatively good agreement with the experimental data of the time‐averaged velocity and the secondary vectors in both the bent tube and straight outlet sections. For example, the location of the maximum streamwise velocity, which appears near the top or bottom wall in the bent tube, is predicted correctly by the present method. As for the comparison of Reynolds stresses, the present method has been found to simulate many characteristic features of streamwise normal stress and shear stresses in the bent tube qualitatively and has a tendency to under‐predict its value quantitatively. Judging from the comparison between the calculated and the experimental results, the algebraic Reynolds stress model is applicable to the developing turbulent flow in a bent tube that is known as a flow with a strong convective effect. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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A non-destructive experimental procedure is presented which enables the determination of residual thermal stresses in optical
fiber preforms. The procedure is based on integrated photoelasticity. We carry out the measurement of the optical retardation
using the traditional Sénarmont compensation method combined with a fringe shifting technique. The radial distribution of
the axial stress is reconstructed using Abel transform. We have investigated two different refractive-index profiles, adopted
in the realization of monomode and multimode optical fibers. It was shown that in both cases the results obtained experimentally
and those analytically predicted by the Timoshenko elastic model were in good agreement. To obtain accurate experimental results,
it was necessary to apply a correction procedure to take into account the fact that the trafectories of the light rays inside
the preforms are not straight lines. 相似文献
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消光比是表征单偏振光纤偏振性能好坏的特征参数之一,影响它的因素有很多,如光谱带宽。结合熊猫型单偏振光纤的测量,搭建了双轴光谱带宽测量系统,通过对单偏振光纤的光谱带宽、消光比参数的大量测量和分析,找到了光谱带宽对消光比参数影响的原因。结论是单偏振光纤的工作波长要远离光谱带宽的下限位置,即HE_(11y)模式的截止损耗峰,另外,要求HE_(11y)模式的截止损耗要陡峭,这样才能保证单偏振光纤具有高消光比特性。 相似文献
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光流测量技术作为一种新的空气动力学实验技术,以其像素级分辨率的矢量场测量优势获得广泛的应用。光流测量技术使用光流约束方程,配合平滑限定条件,可以进行速度场测量,获得高分辨率的全局矢量场。本文首先通过研究积分最小化光流测速理论和算法,采用C++编写光流速度测量程序;然后通过三种典型的人工位移图像对光流计算程序进行了验证,并将结果和标准位移分布进行比对分析,以指导如何在实际应用中获得高精度光流速度场;最后进行小型风洞后向台阶实验,利用高速相机拍摄示踪粒子图像,使用光流计算程序获得速度矢量场,同采用互相关算法的粒子图像测速计算结果相比较,体现出光流计算方法像素级分辨率的矢量场测量优势。 相似文献
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S.A. Pikuz A.Ya. Faenov J. Colgan R.J. Dance J. Abdallah E. Wagenaars N. Booth O. Culfa R.G. Evans R.J. Gray T. Kaempfer K.L. Lancaster P. McKenna A.L. Rossall I.Yu. Skobelev K.S. Schulze I. Uschmann A.G. Zhidkov N.C. Woolsey 《High Energy Density Physics》2013,9(3):560-567
K-shell spectra of solid Al excited by petawatt picosecond laser pulses have been investigated at the Vulcan PW facility. Laser pulses of ultrahigh contrast with an energy of 160 J on the target allow studies of interactions between the laser field and solid state matter at 1020 W/cm2. Intense X-ray emission of KK hollow atoms (atoms without n = 1 electrons) from thin aluminum foils is observed from optical laser plasma for the first time. Specifically for 1.5 μm thin foil targets the hollow atom yield dominates the resonance line emission. It is suggested that the hollow atoms are predominantly excited by the impact of X-ray photons generated by radiation friction to fast electron currents in solid-density plasma due to Thomson scattering and bremsstrahlung in the transverse plasma fields. Numerical simulations of Al hollow atom spectra using the ATOMIC code confirm that the impact of keV photons dominates the atom ionization. Our estimates demonstrate that solid-density plasma generated by relativistic optical laser pulses provide the source of a polychromatic keV range X-ray field of 1018 W/cm2 intensity, and allows the study of excited matter in the radiation-dominated regime. High-resolution X-ray spectroscopy of hollow atom radiation is found to be a powerful tool to study the properties of high-energy density plasma created by intense X-ray radiation. 相似文献
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研究在热载及拉伸共同作用下,光纤传感器涂层的材料特性和厚度变化对光纤-涂层-基体基体性能的影响,分析表明在埋入式光纤附近的应力集中涂层的特性有关。在热应力和机械应力共同作用下,对于给定的基体材料和裸光纤,存在可减少基体,涂层与裸光纤之间或裸光纤中应力集中的涂层性能和尺寸的最优组合。 相似文献