Analysis of Microwave Photonic Notch Filter with Tunable Parameters

In this paper a tunable photonic notch filter based on all-optical mixing using a single narrow-linewidth optical source and a variable time delay line is presented. In the proposed filter, the optical carrier emitted from a laser source is externally intensity modulated by a subcarrier signal and then applied to a second intensity modulator. By using a variable polarization beamsplitter, a Hi-Bi coupler, a variable time delay line; a two-tap photonic microwave notch filter with a tunable free spectral range (FSR) is numerically demonstrated. An expression for the filter transfer function is derived. Numerical results show a notch rejection greater than 30 dB.