CSO distortions due to the combined effects of self- and external-phase modulations in long-distance 1550-nm AM-CATV systems

We found that the combined effects of self- and external-phase modulations must be considered in order to precisely predict the composite second-order distortions in a long-distance 1550-nm externally modulated AM-cable TV (CATV) system, especially when the applied phase modulation index and modulating tone frequency to the integrated phase modulator are high. This result has important implications to the optimum design of 1550-nm transmitter for long-distance AM and QAM-CATV systems.