SUBCARRIER MULTIPLEX OPTICAL TRANSMISSION METHOD AND SUBCARRIER MULTIPLEX OPTICAL TRANSMITTER

摘要

PURPOSE:To improve CSO and CTB of a worst channel by setting the intensity of a subcarrier of a channel having much number of nonlinear distortion caused in a reception band larger than the intensity of other subcarrier. CONSTITUTION:A level of each subcarrier from a subcarrier multiplex signal 1 is adjusted by an emphasis circuit 4, the signal is superimposed on a bias current 5 and the result is fed to a transmission light source 6. A signal light 7 outputted from the transmission light source 6 is received by an optical receiver 11 after the transmission through a single mode optical fiber 10 whose length is 15km. A subcarrier multiplex signal 13 is inputted to a deemphasis circuit 14 having a reverse characteristic to that of the emphasis circuit 4, and after the intensity of each subcarrier is made equal, an output signal 15 is outputted from the optical receiver 11. The emphasis circuit 4 sets the intensity of the subcarrier thereby improving the CSO more than that of a conventional system by 0.63dB.