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一、序言在叙述第四代光纤通信系统之前,简要地回顾一下第一、二、三代系统的特性。第一代系统的工作波长为0.85μm,应用AlGaAs激光器或发光二极管为光源,硅的p-i-n管或APD管为检测器,多模光纤为传输媒介。多模光纤虽然在低损耗、低色散方面不及单模光纤,但它的纤芯直径大,因而有容易制造和容易接配的优点。第二代系统的工作波长为1.3μm,应用InGaAsP的激光器或发光二极管为光源,
I. Introduction Before briefly reviewing the fourth generation of optical fiber communication systems, briefly review the features of the first, second and third generation systems. The working wavelength of the first generation system is 0.85μm, the application of AlGaAs laser or LED as light source, silicon p-i-n tube or APD tube as detector, and multimode fiber as transmission medium. Although multimode optical fiber is inferior to single mode optical fiber in terms of low loss and low dispersion, its core diameter is large, which makes it easy to manufacture and easy to assemble. The working wavelength of the system of the second generation is 1.3μm, use InGaAsP laser or light-emitting diode as the light source,