Reconfigurable microwave photonics filters with negative coefficients based on a quantum dash mode-locked laser

We propose and demonstrate a reconfigurable microwave photonics (MWP) filter with negative coefficients using a quantum dash (QDash) mode-locked laser (MML). Thanks to the large number of comb lines $(\sim 50)$ generated by the QDash-MLL, we can easily tailor the optical frequency comb (OFC) spectrum and the filter responses. The negative taps are enabled through a balanced photodiode (BPD). In the experiment, we realized the flat-top and triangular responses. The proposed MWP filter shows a great tunability. Moreover, the readily packaged QDash-MLL with the large number of comb lines is a promising OFC source for developing integrated and reconfigurable MWP applications.