All-Optical Transversal Filter With Tap Increasing and Negative Coefficients Based on Double-Pass Modulation

A novel microwave photonic filter with tap increasing and negative coefficients is proposed and experimentally demonstrated. The negative coefficient is achieved by employing a phase modulator, while the tap increasing is based on double-pass modulation of a Mach-Zehnder modulator (MZM). The experimental results demonstrated that stable five-tap bandpass filter characteristics can be obtained by using only one optical source. The experimental results of the proposed filters also show tunability and partial reconfigurability.