Theoretical analysis of a hybrid AM-VSB/QAM SCM lightwave system with adjustable preclipping levels

A model for the analysis of the performance of a hybrid multichannel amplitude modulation vestigal sideband (AM-VSB)/quadrature amplitude modulation (QAM) subcarrier-multiplexed (SCM) lightwave transmission system with adjustable preclipping levels is presented. In the proposed model, two-stage adjustable clipping effect due to the preclipper and laser are considered. The analytical result shows that in this hybrid system the bit error rate (BER) is improved while the carrier-to nonlinear distortion (C/NLD) ratio is degraded as the value of the preclipping factor, is decreased, and vice versa. The validity of this model is verified by comparing the theoretical optimal value of /spl tau/ which is derived using our approach with the existed experimental result.