Generation of 20-GHz picosecond pulse trains in the normal and anomalous dispersion regimes of optical fibers

In this paper, we numerically and experimentally study two methods to generate 20-GHz pulse trains at 1550 nm from a dual-frequency beat-signal. The first method is based on the multiple four-wave mixing temporal compression occurring in the anomalous dispersion regime of a standard optical fiber (SMF). In the second original method, the initial sinusoidal signal is first converted into a parabolic pulses train through nonlinear propagation in a normally dispersive fiber. A subsequent linear compression in an anomalous dispersive fiber leads to well-separated picosecond pulses.