? ? 由于近來《分析性思維》課程的引導，我想著去用自己新學的一些知識寫一篇文章，文題定為‘Why we need "Optical amplifier" in Optical-fiber communication’，同時熟悉分析性思維中講述的分析方式方法，具體文章結構在下文中每部分的末尾以加粗的方式標識出。
? ? Why we need "Optical amplifier" in Optical-fiber communication?(Generation Purpose) This article will use method taught in《Analytical thinking》 to make it clear.
? ? It is known to all that gradually coming of era of information, causes the amount of network data increased dramatically, which brings challenges to communication engineering, with the requirement of larger channel capacity of information.(Questions at Issue)
? ? I'll give demonstration for the "Optical amplifier" can satisfy this kind of? 'harsh requirement',
? ? When the Input optical power is at -4~+10dBm, for EDFA, it will at the working condition of APC(自動功率控制), when power reached -10~-4dBm, it will switch to work mode as ACC(自動電流控制),? to output a constant nominal value.(Information)
? ? From the data it can be easily judge that Optical amplifier can satisfy the requirements perfectly and it can save a lot.(Interpretation and Inference)
? ? Without the Optical amplifier, we then have to ask the equipment which can realize "Electrical regenerative relay" for help.
? ? If there is WDM signal input in the optical-fiber, needed to be regenerative, the reality is that each wavelength must be amplified one by one, which complicates the electrical equipment, to make matters worse, it directly limits the transmission distance, and greatly increase the cost of the project.
? ? As a comparison, one optical amplifier can provide gain to multiple channels, and the gain will not be affected by the polarization of the signal. Further more, crosstalk will not occur in high rate and multi-channel transmission systems, nor will pulse distortion occur in it.
? ? To the ultimatum, once optical amplifier is being used, it will bring huge advantages for communication engineering.(Assumptions)
? ? It can be highly appraised the appearance of the Optical amplifier makes the WDM technology move from theory to practice, besides, it promotes the development of optical soliton technology and All-optical communications network, in a word, make the optical-fiber communication technology has produced a qualitative leap.(Implications and Consequences)
? ? That is why we tend to make it widely used in both experimental and commercial communication systems, ie. the WDM systems, Optical amplifier deserves the called as a key component in WDM systems.(Point of View)
