A Photonic Comb Filter With Independently and Digitally Tunable Bandwidth and Frequency Spacing

A photonic comb filter with digitally tunable bandwidth and frequency spacing is proposed. Using cascaded differential-group-delay (DGD) element and polarization switch based filters, we demonstrate independent tunability of both parameters with >; 12-dB first-sidelobe reduction for a 6-bit configuration. Limitations of such an approach are also discussed.