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光发射机的任务是把从前端送来的高频电视信号变成光信号,使其能在光导纤维中传输。光发射机按照调制方式来划分有调频、调幅和数字调制等多种。目前用得最多的是多路调幅光发射机,在调幅光发射机中按照强度调制的方式不同又分为直接调制光发射机和外调制光发射机。直接调制光发射机是利用高频电视信号(将信号电流叠加到激光器的偏置电流上)来控制半导体激光器的偏流,进而控制激光器
The task of an optical transmitter is to convert the high-frequency television signal sent from the front into an optical signal so that it can be transmitted in the optical fiber. Optical transmitters in accordance with the modulation to divide FM, AM and digital modulation and other. At present, the multi-way amplitude modulation optical transmitter is the most used, and is divided into a direct modulation optical transmitter and an external modulation optical transmitter according to the intensity modulation method in the amplitude modulation optical transmitter. Directly modulated optical transmitter is the use of high-frequency television signal (the signal current superimposed on the laser bias current) to control the semiconductor laser bias current, and then control the laser