Continuously Tunable Microwave Photonic Filter With Negative Coefficients Using Cross-Phase Modulation in an SOA-MZ Interferometer

A notch filter with negative tap is proposed based on exploiting cross-phase modulation in a semiconductor optical amplifier Mach-Zehnder interferometer. This configuration shows a high operation bandwidth and reduces the chirp of the modulated signal compared to prior proposed configurations based on cross-gain modulation. We compare the operation of the structure when optic delay lines or dispersive fibers are used to generate the optical taps. Moreover, a continuous free-spectral range tuning is shown.