Power penalty for optical signals due to dispersion slope in WDM filter cascades

We calculate the receiver power penalty due to the accumulated dispersion s lope of optical filter cascades in wavelength-division-multiplexed optical networks. For flat-top fiber Bragg grating and thin-film filters, dispersiv e rather than amplitude filter effects dominate the cascade power penalty, which increases with dispersion slope and signal frequency detuning from th e cascade zero-dispersion point. The dispersion slope of these filters vari es as the inverse cube of their bandwidth, causing increased penalties for narrow filters in systems with small channel spacing. For a 60-GHz-wide Bra gg grating filter with a 1.3-ns/nm(2) dispersion slope, a cascade of 26 fil ters can be tolerated at 10 Gbit/s with +/-5 GHz allowed detuning. Opticall y preamplified receivers have significantly larger dispersion penalties tha n thermal-noise-limited receivers.