Dispersion-induced power penalty in fiber-Bragg-grating WDM filter cascades using optically preamplified and nonpreamplified receivers

In wavelength-division-multiplexed optical networks, signals pass through cascades of multiplexing/demultiplexing channel filters present in the network access nodes. We describe experimental measurements and numerical simulations of the signal power penalty at 10 Gbps due to dispersion slope in such a cascade of fiber-Bragg-grating filters. The dispersion penalty of the cascade limits the allowed frequency detunings of the signal laser and channel filters. We observe that optically-preamplified receivers show a significantly larger dispersion penalty than nonpreamplified receivers, with a simple relation between the two penalties. This penalty difference should exist for any signal impairment that degrades optical signal extinction such as dispersive filter or fiber transmission and optical channel bandwidth narrowing.