Optical transmitter for subcarrier frequency multiplexed optical transmission system

摘要

The subcarrier frequency multiplexed optical transmission system disclosed is one in which a plurality of analog subcarrier signals (101 to 160) and at least one digital subcarrier signal (201) is optically transmitted by frequency multiplexing. The system includes an amplitude limiter (300), a filter (400), a multiplexer (410) and a semiconductor laser (500). Portions of the analog subcarrier signals (101 to 160) which are lower in level than the threshold value of the semiconductor laser (500) are eliminated by the amplitude limiter (300), and further impulse distortions generated due to clipping in the frequency band of the digital subcarrier signal (201) are eliminated by the filter (400). Then, the analog and digital subcarrier signals (101 to 160 and 201) are frequency multiplexed to be inputted to the semiconductor laser (500). The system enables to reduce the transmission quality deterioration of digital subcarrier signal caused by clipping.