Experimental verification of self-phase-modulation-induced nonlinear distortion in externally modulated AM-VSB lightwave systems

Self-phase-modulation (SPM) in intensity-modulated systems causes frequency chirp, which in combination with fiber dispersion generates second-order distortion. It has been shown theoretically that in externally modulated systems, this effect can cause intolerable amounts of composite second-order (CSO) distortion, if the length of the feeder section between the CATV head-end and the local exchange exceeds a few tens of kilometers. We will for the first time present experimental data, supporting the theoretical analysis.