Investigation of the effect of an increased supervisory signal power in a high-loss loopback monitoring system

We present experimental results for the effect of an increased supervisory signal power in a high-loss loopback supervisory system in an optically amplified WDM transmission line. The paper focuses on the investigation of increasing the input power for the supervisory signal and the effect on the copropagating WDM data signals using different channel spacing. This investigation is useful for determining the power limitation of the supervisory signal if extra power is needed to improve the monitoring. The paper also shows the effect of spacing on the quality of the supervisory signal itself due to interaction with adjacent data signals.