All-optical WDM microwave filter with negative coefficients

A novel all-optical incoherent microwave filter with negative coefficients based on multiple optical carriers and a dispersive medium is presented. Negative coefficients are obtained by means of the /spl pi/ phase inversion in a single electrooptic Mach-Zehnder modulator and the modulator V/sub /spl pi// dependence with wavelength. In this way, negative coefficients can be implemented using a single modulator. Finally, experimental results for a notch filter showing the feasibility of the technique are provided.