The use of semiconductor-optical-amplifiers for long optical links in the CATV upstream optical network

The use of 1550-mm external transmitters and optical amplifiers in the CATV downstream system leads to long and high-loss optical links for upstream transmission. Additionally, the deployment of internet services has increased the constraints on the upstream optical link. These two-system characteristics, taken together, require a new approach for the upstream optical link. In this letter, we present the use of semiconductor optical amplifiers (SOAs) to overcome these constraints. We show, through experiment and theory, that a SOA used as an optical preamplifier increases the dynamic operating window 11 dB for optical links of 85 km.