A tunable photonic microwave notch filter using a multiple wavelength optical source

We propose a tunable photonic microwave notch filter using a multi‐wavelength optical source. Two peak wavelengths are generated using a reflective semiconductor optical amplifier (RSOA) self‐injection, locked by two external fiber Bragg gratings (FBGs). The time delay required for the notch filter is obtained based on the wavelength‐dependent propagation velocity through the fiber. The tunable filter characteristic is obtained by changing the center wavelength of one of the gratings and its tunability is limited only by the gain profile of the RSOA and the tuning range of the grating. Based on the proposed structure, a two‐tap microwave notch filter with free spectral range tunable from 1.15 to 5.79 GHz is experimentally demonstrated. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 134–138, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24841