Increased Nonlinear Crosstalk in Analog Wavelength-Division-Multiplexed Links Due to the Chromatic Dispersion of Optical Filters

The effect of the chromatic dispersion of an interference filter on the nonlinear crosstalk in a wavelength-division-multiplexed microwave photonic system is investigated. For a simple two-channel pump–probe system with 200-GHz channel spacing, a crosstalk variation of greater than 30 dB is observed as the wavelength of the probe is varied across the flat-top region of the filter. The crosstalk is correlated with the dispersion of the filter and a variation of less than 7% of the filter width is observed to increase the crosstalk by 10 dB. An analytical model for calculating the crosstalk is presented.