共查询到19条相似文献,搜索用时 78 毫秒
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在光纤通信系统中,用于传输信息的光纤按其传输特性又要分为单模光纤和多模光纤,在此我就其传导模式,各自特性及一些重要参量对单模光纤和多模光纤进行简单介绍。 一、光纤的传导模式 我们知道,由于光在不同介质中的传播速度不同,光线经过两个不同介质的交界面时,就产生折射。当光线由光密媒质射向光疏媒质,其折射角将比入射角大。我们适当改变入射角时,会使折射角Qo= 相似文献
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色散是光纤的传输特性之一。由于不同波长光脉冲在光纤中具有不同的传播速度,因此,色散反应了光脉冲沿光纤传播时的展宽。光纤的色散现象对光纤通信极为不利。光纤数字通信传输的是一系列脉冲码,光纤在传输中的脉冲展宽,导致了脉冲与脉冲相重叠现象,即产生了码可干扰,从而形成传输码的失误,造成差错。为避免误码出现,就要拉长脉冲间距,导致传输速率降低,从而减少了通信容量。另一方面,光纤脉冲的展宽程度随着传输距离的增长而越来越严重。因此,为了避免误码,光纤的传输距离也要缩短。光纤的色散可分为: 相似文献
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半导体激光器与单模光纤的耦合—理论与实验研究 总被引:1,自引:0,他引:1
本文介绍半导体激光器与单模光纤耦合的理论与实验研究.采用拉锥光纤,实验测量的高功率大辐射角半导体激光器与单模光纤之间的耦合效率为44%. 相似文献
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大芯径多模石英光纤端面耦合技术研究 总被引:7,自引:0,他引:7
对大芯径多模光纤端面耦合技术进行了研究,实验测量了光纤端面间的横向偏离、轴向偏离及光纤轴夹角对耦合效率的影响,其中光纤端面间的横向偏离对耦合效率影响较大,这些实验结果对大芯径多模光纤端面间的连接或熔接以及提高耦合效率具有一定意义。 相似文献
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在入射光瞳面处针对星地激光链路中空间光至单模光纤耦合效率补偿特性进行了研究,依据星地下行链路特点,对星地下行链路光纤耦合效率模型进行分析。在此基础上,利用基于单模光纤后向传输模场为加权函数的加权孔径正交多项式,建立光纤耦合接收系统波前相位模式补偿理论模型,运用该理论模型,通过数值模拟对波前相位进行模式补偿,给出波前相位模式补偿下平均光纤耦合效率与接收孔径尺寸和相位补偿项数的变化关系,以及典型接收孔径下采取一定项数的波前相位补偿后光纤耦合效率概率分布,为基于光纤耦合接收方式的星地激光通信链路波前补偿系统设计提供一定理论参考。 相似文献
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A method for obtaining permanent low-loss couping between arrys of single-mode fiber and Ti:LiNbO3 waveguides is described. The technique, based on the use of silicon chip V-grooves, simplifies the coupling problem by simultaneously aligning the entire array and by providing a large surface area for a higher integrity adhesive bond. Atlambda = 1.3 mu m, we measure an average 1.9-dB coupling loss (exclusive of propagation loss) for the assembled array. The average excess loss due to the fiber array is 0.8 dB. We present an analysis of the effect of various types of array misalignment on coupling efficiency. Angular alignment and array periodicity are found to be critical. If the fiber and waveguide periodicities are matched exactly, the fibers need only be placed withinpm 1.3mu m of their optimum position to maintain coupling efficiencies greater than 90 percent. 相似文献
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Tapered single-mode optical fiber evanescent coupling 总被引:1,自引:0,他引:1
We describe the results of a numerical and experimental investigation of how a point source of radiation couples light to the HE 11 mode of a tapered single-mode fiber. Specifically, we have investigated two different geometries of nonadiabatic, tapered single-mode optical fiber. The motivation for this study is the characterization of a single-mode tapered optical fiber biosensor. In such a device light is collected from fluorescent sources located along the cladding surface of the tapered fiber. Taper-to-taper coupling measurements and fiber mode calculations indicate the device sensitivity decreases exponentially as sources are moved away from the tip of the tapered fiber 相似文献
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An effective method for coupling optical signals from single-mode fibers to thin-film waveguides is proposed. The authors show that this method provides high coupling efficiency for connecting fibers of different core diameters to thin-film waveguides of different film thicknesses or refractive indexes. The authors summarize the theoretical treatment of the coupler. Examples of couplers designed for SiO2 -based materials as well as iron garnets are presented. Fabrication of the proposed coupler and its experimental results are described 相似文献
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近年来由于单模光纤研究的极大成功,促进了单模光纤通信系统和单模光纤应用技术的迅速发展。单模光纤的实际损耗已降到接近理论值,因此为进一步改善单模光纤传输系统的信噪比,提高激 相似文献
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Snowbell M. Strasman N. Fischer B. Cronin-Golomb M. 《Lightwave Technology, Journal of》1995,13(1):55-61
We present and demonstrate a method for efficient coupling of many beams into a single-mode fiber. Using the phase conjugating property for mutually incoherent beams of the double phase conjugate mirror (DPCM), we achieved coupling for a full 6×6 matrix of beams into a single-mode fiber. In principle, this number of input channels can be increased manyfold beyond the 36 used in our experiment. Of the phase conjugate generated by the DPCM in the direction of the fiber, over 97% (Fresnel corrected) entered the fiber, thus giving a highly accurate coupling. The DPCM transmission efficiency itself was measured at 40% (Fresnel corrected), thus giving an overall coupling efficiency of 39%. By optimizing the DPCM parameters, a significantly higher overall coupling could be achieved. An additional advantage of this method is that the DPCM will reconfigure if there are small changes in the system, thus making the system very robust. This multichannel coupling method can be of importance in the coupling of the output beams of a vertical cavity surface emitting laser (VCSEL) into a single-mode fiber where each channel may carry independently modulated information. This technique can be further generalized to a bidirectional multisingle-mode fiber interconnection system, of which a basic 3×2 system is demonstrated 相似文献
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We have achieved a single-mode fibre to waveguide to fibre total insertion loss as low as 1 dB for a 1 cm-long titanium-diffused lithium niobate waveguide. 相似文献