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1.
单模光纤弯曲损耗的测量与分析   总被引:1,自引:0,他引:1  
从理论和实验两方面讨论了弯曲半径及工作波长对单模光纤弯曲损耗的影响,测量了1310nm和1550nm波长光作用下,弯曲损耗随弯曲半径的变化关系。结果表明:随着弯曲半径的增大,弯曲损耗系数呈下降趋势,并且伴有振荡现象出现;而且,在弯曲半径较大时,弯曲损耗变化平缓,1550nm波长较1310nm波长明显更易产生弯曲损耗,而小弯曲半径对应的弯曲损耗振荡剧烈,此时两种光波长对弯曲损耗的敏感程度交替变大。  相似文献   

2.
光纤弯曲损耗特性的理论与实验研究   总被引:2,自引:1,他引:2  
为了减小在长距离光纤通信中存在的弯曲损耗和利用光纤激光器中的弯曲损耗获得单模输出,利用速度法解释了光纤弯曲损耗机制,采用Marcuse理论研究了弯曲损耗随弯曲半径、波长和纤芯半径变化的关系。通过计算机仿真和实验得出弯曲损耗随弯曲半径的减小而增大,随波长的增大而增大,随纤芯半径的增大而增大,高阶模式的损耗大于低阶模式。利用这一结论就可以通过控制弯曲半径在临界半径以内来减小通信中的弯曲损耗,通过增大模场半径来实现光纤激光器中的单模输出。  相似文献   

3.
提出用光纤环腔衰荡技术研究单模光纤的弯曲损耗及其随弯曲半径和温度变化的振荡特性。光纤弯曲时,从基模辐射出去的一部分能量在包层-涂敷层或涂敷层-空气界面处发生反射形成回音壁(WG)模,当满足同向耦合条件时,WG模又重新耦合回纤芯与基模发生干涉,使光纤的弯曲损耗产生振荡。实验结果表明,在弯曲半径为9.33~27.63 mm的范围内,单模光纤的弯曲损耗除了随弯曲半径的减小呈指数增大外,还伴随有振荡现象,且WG模与纤芯基模之间还会发生二阶耦合,导致次级振荡的存在;弯曲损耗随温度的变化也存在振荡现象,振荡周期随温度的升高和弯曲半径的减小而减小。实验得到的振荡峰的位置和幅值及振荡周期与理论分析结果一致。  相似文献   

4.
光子晶体光纤的弯曲损耗振荡特性分析   总被引:2,自引:1,他引:1  
崔莉  赵建林  张晓娟  杨德兴 《光学学报》2008,28(6):1172-1177
综合运用弯曲光纤的等效直光纤模型、全矢量频域有限差分法及各向异性完全匹配层吸收边界,计算了两种类型(折射率引导型和带隙型)光子晶体光纤(PCF)的弯曲损耗.通过数值模拟弯曲损耗随弯曲半径的变化关系,证实了两种光子晶体光纤均具有弯曲损耗振荡特性.进而分析了两种光子晶体光纤弯曲损耗振荡的产生机理并给出了与损耗峰对应的包层模式.结果表明,振荡的产生源于基模与包层模式的耦合,其中,折射率引导型光子晶体光纤的弯曲损耗振荡机理类似于传统双包层光纤,带隙型光子晶体光纤弯曲损耗振荡的产生则是两种不同类型的包层模式共同作用的结果.  相似文献   

5.
掺钕光纤放大器的弯曲损耗对增益的影响   总被引:1,自引:1,他引:0  
孔勇  郭明秀  陆雨田 《光子学报》2003,32(8):900-903
利用掺钕光纤放大器的粒子数速率方程、功率传输方程和光纤弯曲损耗公式,对光纤弯曲损耗所引起的增益变化进行了数值模拟,分析了对于不同半径和波长下光纤弯曲损耗对光纤增益的影响,结果表明,对于一定长度的光纤,其增益随弯曲半径的减小而减小,当弯曲达到一定值时,增益发生急剧的降低;随弯曲半径的减小,其增益谱线发生下移,这对实验研究有着重要的指导意义。  相似文献   

6.
光子晶体光纤弯曲损耗特性研究   总被引:2,自引:3,他引:2  
郭夏锐  杨德兴  赵建林  杨青  杜旭荣 《光子学报》2007,36(10):1817-1820
对光子晶体光纤的损耗特性进行了分析,并在实验上对两种典型的光子带隙型和全内反射型光子晶体光纤进行了研究.分别对两种不同结构的光子晶体光纤在弯曲半径2~15 mm范围内的损耗进行了测量.与传统光纤损耗实验结果的对比表明,两种光子晶体光纤的弯曲损耗均不明显,具有很强的抗弯曲损耗能力.实验也证实了光子晶体光纤弯曲损耗存在临界弯曲半径,在大于临界半径的情况下,几乎没有弯曲损耗.从结构上分析并证明光子晶体光纤弯曲损耗随填充比(d/Λ)的增加而减小,填充比越高弯曲损耗越小.  相似文献   

7.
波导弯曲半径与弯曲损耗的关系   总被引:8,自引:4,他引:4  
介绍了分析波导弯曲损耗的保形变换法和归一化方法以及由此得到的波导弯曲半径与弯曲损耗的关系式.建立了弯曲损耗经验公式,由该公式得出了四种常用材料的波导弯曲半径与弯曲损耗的曲线,并将已报道的相应材料制作的AWG中的最小弯曲半径及其对应的损耗实验数据与这些曲线上的相应数值进行了比较,结果表明,弯曲损耗经验公式在确定AWG中的最小弯曲半径时,有一定的参考价值.  相似文献   

8.
冯向华  季家镕  窦文华 《光学学报》2012,32(8):823003-201
研究了用于光互连的聚硅氧烷多模光波导直接弯曲时弯曲损耗与圆弧曲率半径的关系。用Marcuse的直波导近似法理论计算了其弯曲损耗,理论计算表明弯曲损耗随模阶数的增加而变大,随半径的减少而变大;光在波导中传输时,总弯曲损耗出现阶跃式变化,并且曲率半径大于4 mm时,波导的弯曲损耗小于1dB/cm。用BeamPROP仿真软件仿真了5、10、20mm三种曲率半径下的传输光场情况。利用数字化散射法测量了其弯曲损耗,实验结果显示曲率半径在5~6mm时弯曲损耗值在0.55~0.8dB/cm之间,考虑所制备的聚硅氧烷直波导固有的传输损耗,实验值与理论值基本相符。  相似文献   

9.
为了研究分布反馈光纤激光器的弯曲特性,对光纤激光器输出波长和弯曲半径的关系进行了理论分析和实验研究.理论分析表明,光纤激光器输出波长变化量与弯曲半径平方的倒数为线性相关,并且随着弯曲半径的增大布拉格波长向短波长方向移动;实验中通过对3支不同波长的光纤激光器在弯曲半径分别为1O mm、20 mm、90 mm时输出波长的测...  相似文献   

10.
本文对聚合物阵列波导光栅(AWG)波分复用器中波导的弯曲损耗进行了理论分析。为了使AWG器件中单模传输时波导的弯曲损耗尽量地减小,结合计算实例对波导的弯曲半径、弯曲角度和弯曲弧长等几何参量的选择进行了适当的讨论。  相似文献   

11.
In this paper, the bend characteristics of the single mode-multimode-single mode (SMS) fiber structure are experimentally investigated. SMS fiber structure is very sensitive to the bend. The central wavelength shifts to shorter wavelength with the increasing of fiber bend angle. The central wavelength shift changes with the changing of multimode fiber(MMF) bend section length. The shorter bend MMF has higher sensitivity to the bend angle.  相似文献   

12.
The use of ultrasonic guided waves for the inspection of pipes with elbow and U-type bends has received much attention in recent years, but studies for more general bend angles which may also occur commonly, for example in cross-country pipes, are limited. Here, we address this topic considering a general bend angle φ, a more general mean bend radius R in terms of the wavelength of the mode studied and pipe thickness b. We use 3D Finite Element (FE) simulation to understand the propagation of fundamental axisymmetric L(0, 2) mode across bends of different angles φ. The effect of the ratio of the mean bend radius to the wavelength of the mode studied, on the transmission and reflection of incident wave is also considered. The studies show that as the bend angle is reduced, a progressively larger extent of mode-conversion affects the transmission and velocity characteristics of the L(0, 2) mode. However the overall message on the potential of guided waves for inspection and monitoring of bent pipes remains positive, as bends seem to impact mode transmission only to the extent of 20% even at low bend angles. The conclusions seem to be valid for different typical pipe thicknesses b and bend radii. The modeling approach is validated by experiments and discussed in light of physics of guided waves.  相似文献   

13.
线圈型全光纤偏振器的研究   总被引:2,自引:0,他引:2  
贾波  胡力 《光子学报》1998,27(9):842-846
本文采用等效电流法对线圈型全光纤偏振器进行了分析计算.对应于保偏光纤中两正交传输基模的消光比,提出了一种分析保偏光纤弯曲损耗的新方法,这种方法基于将保偏光纤两个不同偏振模式分别等效为两个普通圆光纤的基模,等效参数通过测量不同偏振模式的模场半径来确定.实验证明这种理论计算方法与实验结果一致.最终,我们研制出的线圈型光纤偏振器在1.31μm工作波长下,实测消光比达30dB以上,工作偏振模式插入损耗≤3dB.  相似文献   

14.
对弯曲不敏感的长周期光纤光栅传感器   总被引:6,自引:5,他引:1  
发现了用高频CO2激光写入的长周期光纤光栅的谐振波长对弯曲灵敏度在圆周的不同方向上呈现周期性,且在两个特定的对称方向上对弯曲不敏感(即弯曲曲率达到1.1m-1,谐振波长仅漂移-0.018nm).据此提出新型对弯曲不敏感的传感器和可调灵敏度弯曲传感器的设计方案,可望从根本上解决长周期光纤光栅在测量中存在的温度、应变或折射率与弯曲之间的交叉敏感问题.  相似文献   

15.
A novel bend-insensitive long-period fiber grating (LPFG) sensor written using focused CO2 laser pulses is demonstrated, for the first time, to our knowledge. It is found that the central wavelength shift of such a LPFG is only −0.018 nm even for a curvature of 1.1 m−1 at the most bend-insensitive position of the LPFG. Experimental results show that the bend sensitivity of the central wavelength of the LPFG has a periodic distribution along its circular directions. Such a bend-insensitive sensor could be used to solve the problem of cross-sensitivity between bend and other measurands, such as temperature, strain or refractive index, which is an unsolved problem for LPFG sensors in practice. In addition, the bend sensitivity of the LPFG can be adjusted by selecting its circular positions.  相似文献   

16.
Calculation of bend loss for single-mode graded-index fibers utilizes the fundamental modal field. Using some of the single and two parameter scalar variational approximations available in the literature for this mode, the bend loss has been computed. The exact results are obtained using a well known numerical method. The accuracies of the results obtained from the use of these variational fields have been compared.  相似文献   

17.
A simplified scheme of bend-induced mode distortion is introduced into bent holey fibres, the distorted mode distribution and mode effective area reduction are investigated using the finite difference method. Numerical results show that the modes of bent holey fibres with small bend radius shift away from the core and are deformed greatly, and the mode areas drop significantly as the bend radius decreases, which severely affects the fibre laser performance. The propagation characteristics of bent holey fibres at given wavelength are determined by fill factor and normalized bend radius. Finally, the transition normalized bend radius that represents the location of the mode area beginning to fall off is obtained.  相似文献   

18.
高频CO2激光脉冲写入长周期光纤光栅的弯曲特性分析   总被引:2,自引:1,他引:1  
分析了高频CO2激光脉冲写入的长周期光纤光栅弯曲的谐振波长漂移灵敏度、谐振峰幅值变化的机理,讨论了新型长周期光纤光栅弯曲方向相关性并进行了数值计算,分析结果与实验结果相符.  相似文献   

19.
The cutoff wavelength λc as defined by the CCITT can be defined equivalently as that wavelength for which the attenuation of the second-order LP11 mode is 19.34 dB higher than the attenuation of the fundamental mode. This equivalent definition of λc does not depend on the length and curvature of the fiber. Both measuring methods for λc, the bending method and the multimode reference method, are analyzed and the measurement conditions that lead to the CCITT cutoff wavelength are indicated. The bend attenuation of the second-order mode of a typical matched-cladding, step-index fiber is calculated numerically, and methods are described to determine the length and curvature dependence of the cutoff wavelength from the bend loss data.  相似文献   

20.
对器件用特种单模光纤的弯曲损耗进行了理论分析,并采用Matlab对弯曲损耗进行了仿真数值分析,研究了单模光纤宏弯损耗和微弯损耗随光纤波导结构及波长的变化规律,并优化了光纤波导结构,开发出抗弯性能优良的单模光纤,同时具有较低的熔接损耗。  相似文献   

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