Impact of concatenated AWG filters in metro transparent network with DML

This paper studies the impact of concatenated AWG routers of metro transparent network with directly modulated lasers (DML). The wide bandwidth and central frequency shift of the directly modulated laser entail a large signal penalty, thereby limiting the allowable number of AWG routers in a metro network. The degradation caused by the concatenation of passband-flattened AWG is much lower than that of the conventional round-top AWG of the same number. Therefore the passband-flattened AWG has the largest allowable number in the metro network based on DML.