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1975年,第一代光纤通讯一问世,就显示出其具有比铜线电缆大得多的信息传递量的特点。但是,第一代到第三代光纤都是氧化硅光纤。光信号在氧化硅光纤核心传递时,其信号会变宽且强度减弱,光纤内的一些缺陷及杂质也会吸收或散射光信号强度。这些,都制约着光纤的信息传递量和传递距离的增加。 第四代光纤通讯,采用调制频率或相位的方式来代替以往的强度调制,这是一种相干光通信,光
The first generation of fiber optic communications, in its first form, appeared in 1975 to have a much larger amount of information transfer than copper wire cable. However, first-generation to third-generation optical fibers are silica optical fibers. When the optical signal is transmitted in the core of the silica fiber, its signal will be broadened and its intensity will be weakened. Some defects and impurities in the fiber will also absorb or scatter the optical signal intensity. These are restricting the fiber optic transmission of information and transmission distance increases. The fourth generation of optical fiber communications, the use of modulation frequency or phase approach to replace the intensity modulation, which is a coherent optical communications, light