Improving Nonlinear Effects by Cascading EDFA and RFA in Long-Haul CATV Transmission Link

This paper proposes a long-haul CATV system designing scheme with Erbium doped fiber amplifier (EDFA) and Raman fiber amplifier (RFA) cascaded in the transmission link. The scheme deploys a EDFA as forward pumping in order to utilize its large gain and the quality of ensuring high carrier-to-noise ratio (CNR), and deploys a RFA as backward pumping so as to utilize its distributed structure to get lower nonlinear indices including composite second order (CSO) and composite triple beat (CTB) distortion. Experiment designed in this paper has shown that the scheme proposed can not only ensure CNR in a high level thus ensure the clarity of TV image, but effectively control nonlinear effects so as to avoid TV channel overlapping as well.