单偏振单模微结构聚合物光纤理论设计

采用全矢量有限元法并结合完美匹配边界条件,设计实现了一种新型结构的单偏振单模（single polarization single mode,SPSM）微结构光纤（Microstructured optical fibers,MOFs）,以聚合物聚甲基丙烯酸甲酯（polymethyl methacrylate,PMMA...     

单模与多模光纤光场的统计相关性

用准均匀光源及部分均匀相干光源分别处理多模及单模光纤,利用二阶统计相关函数及角相关函数计算了光纤端面及衍射场的光场统计性质,得到了光纤横向相关长度、角相关长度、有效发光孔径角、光强分布等参数,并与实验进行了比较。     

大模场单模增益光纤的研究进展

高功率光纤激光器的发展面临着各种非线性效应和输出模式和功率不稳定等技术瓶颈,而大 模场单模光纤被认为是解决该类问题的主要手段。 本文系统总结了各种典型的大模场单模增益光纤,阐述了各种光纤的 结构特点以及实现原理,重点分析 了光纤的模场面积、输出功率、抗弯曲特性、激光光束质量和制备难度等几项关键指标。最 后介绍了作者最新设计的新型异质包层螺旋侧漏大模场 单模光纤结构模型及其实现路径,该光纤芯径在50～200μm范围内 具有可调控性,且制备相对简单,有望成为大模场单模光纤 发展的一个新的方向。     

Guided optical waves in fibers with negative dielectric constant

We classify and discuss all optical guided modes able to propagate in ideal metallic-dielectric structures having the symmetry of a step index fiber. The cases of a metallic core with a dielectric cladding and a dielectric core with a metallic cladding are considered. In each case, the intensity profile of the allowed guided modes is shown. The geometric and frequency dispersion of the effective index of the modes is discussed as a function of the optogeometrical parameters of the fibers     

Spring constant in the buckling of dual-coated optical fibers

An exact formula for the spring constant in the buckling of dual-coated optical fibers is obtained on the basis of the solution to a two-dimensional theory-of-elasticity problem. This formula considers the compliance of both the primary and the secondary coatings. It is shown that the formula obtained by Vangheluwe, assuming absolutely rigid secondary coating, could result in an overestimation of the spring constant and, hence, in the overestimation of the critical force value     

Mach-Zehnder interferometer based on core-cladding mode coupling in single mode fibers

In this paper,a novel simple but effective method is presented to construct compact all-fiber Mach-Zehnder (M-Z) interferometer based on CO2-laser-machined micro-notches in single mode fibers.Interference fringes are obtained,and temperature,force,and bending characteristics of the interferometer have been experimentally investigated.Such a compact fiber component with acceptable sensing performances makes it a good candidate for the measurement of numerous physical parameters.     

Time evolution of polarization mode dispersion in optical fibers

The fluctuation of polarization mode dispersion (PMD) due to environmental change is an important issue for fiber-optic communication systems. We measure the time evolution of PMD for installed aerial and buried cables and for a spooled fiber in a temperature controlled chamber. The results show that PMD fluctuates much more rapidly for aerial cables than for buried cables. The magnitude of PMD is different for the three fibers and our results also show that the magnitude of PMD fluctuation depends on the magnitude of the PMD     

Temperature dependence of chromatic dispersion in single mode fibers

This paper describes the temperature dependence of chromatic dispersion in single-mode fibers for a temperature range of -60°- 250°C. Highly accurate dispersion measurements demonstrated a linear relationship (0.025 nm/°C) between the zero dispersion wavelength and temperature for tests conducted below 150°C. Further tests in the high-temperature range showed an increase in this dependence. For both temperature ranges, the results were independent of fiber coating and structure.     

现代单模光纤的改进及其制造技术

回顾了通信用光纤的发展历史，综述了最新发展的几种单模光纤，阐述了它们的几个关键参数与应用范围，描述了它们的制造技术。     

Parallel transmission of images through single optical fibers

The characteristics and limits of parallel transmission of two-dimensional imagery through single optical fibers are reviewed, and methods for overcoming the inherent smearing that occurs at the output are discussed. These solutions include: a) control of the fiber's refractive index profile; b) incorporation of complex filters; and c) encoding the information at the input and decoding the output after transmission.     

Optical transmission in dispersion-shifted single mode spliced fibers and cables

Dispersion-shifted single mode fibers have been fabricated with losses as low as 0.21 dB/km in the zero-dispersion region (lambda_{0} approx 1.5-1.6 mum). Low-loss (average = 0.06-dB) fusion splices have been made with the chlorine-hydrogen flame fusion technique. The recoated splices show strengths in excess of 300 kpsi. The fibers have been incorporated into a cable structure with negligible change in loss.     

Backscattering signatures from optical fibers with differential mode attenuation

The effect of differential mode attenuation (DMA) on backscattering signatures of multimode graded-index fibers is investigated experimentally and theoretically. Differential mode attenuation curves are determined for various commercial fibers and subsequently used to predict the backscattering response of the fibers. Theory and experiment indicate that only small variations in the local backscatter attenuation coefficient appear between various mode-filtered excitations of a given fiber.     

单模光纤中椭圆双折射下偏振模色散特性研究

为了分析椭圆双折射对偏振模色散的影响,将模型中的偏振模色散(PMD)矢量及极化相关损耗(PDL)矢量设定为椭圆偏振矢量,应用保偏光纤(PMF)级联模型和蒙特卡罗仿真方法,研究在PDL影响下的PMD统计特性。研究表明,PMD和PDL矢量的椭圆偏振程度对PMD的统计分布和均值大小均会有影响;在椭圆偏振和PDL的联合影响下,PMD的统计分布为Maxwell和Gaussian分布的合分布。研究结果对偏振模色散的测试、补偿和系统设计均具有参考价值。     

Propagation constant of weakly guiding optical fibers: a neweigenvalue condition

After Laplace transforming the reduced radial Helmholtz equation for a weakly guiding optical fiber, we derive an eigenvalue condition for its propagation constant. It is expressed in terms of the ratio of two Laplace-transformation integrals. We show the usefulness of this new condition in connection with the numerical solution of the scalar Helmholtz equation     

Normalised power transmission in single mode optical branching waveguides

A useful design expression for normalised power transmission in single mode optical branching waveguides has been obtained, where the power transmission is determined only by the normalised waveguide thickness and normalised branching angle. The effect of blunting of the wedge tip of the branching is also investigated.     

Spontaneous Raman scattering and polarization mode coupling in polarization-maintaining optical fibers

Interaction between spontaneous Raman scattering and polarization mode coupling in a polarization-maintaining fiber has been theoretically analyzed. Expressions for the scattered intensity for CW and pulsed excitation are established in terms of practical fiber parameters. Implications of these results to spectroscopy and sensor applications are discussed.     

Mode coupling and equilibrium mode distribution conditions in plastic optical fibers

The equilibrium mode distribution (EMD) condition is critical for optical fiber measurements. In this letter, we examine the achievement of EMD condition inside plastic optical fibers (POF's) under different launch conditions. Our pulse broadening measurements of step-index (SI) POF's as a function of fiber length show that the EMD condition can readily be achieved in an SI POF much shorter than in glass optical fibers. The observation of the EMD condition was also independently verified using the far-field pattern technique.     

New method to calculate mode conversion coefficients in SI multimode optical fibers

A simple method is proposed for the experimental calculation of the mode conversion coefficients in multimode optical fibers. It only requires observing the far-field output pattern from a fixed length of fiber as the launching angle changes, as well as the intersection point between two far-field output patterns corresponding to two different input angles. The results obtained with this method are quite insensitive to small variations of the experimental parameters. A good agreement between theoretical and experimental results is also found.     

单模单偏振光纤基模截止波长的测量

本文给出了单模单偏振光纤基模截止波长的测量原理和测量装置，对W－型单模单偏振光纤的基模截止波长进行了测量，并将测量结果和数值计算进行了比较，它们较好的吻合一致。