In this work, we investigate the generation of stable 20- and 40-GHz pulse trains through the nonlinear compression of an initial beat-signal in a cavity-less optical-fiber-based device. Enhanced temporal stability is achieved by generating the sinusoidal beating thanks to a commercial LiNbO3 intensity modulator driven by a half repetition-rate external RF clock. We also show that the residual timing jitter induced by the RF phase modulation imposed to suppress Brillouin back-scattering can be reduced by managing the cumulated dispersion of the compression line, whereas complete polarization stabilization is obtained owing to a modified setup involving a Faraday rotator mirror. Finally, a high-quality 160-Gbit/s signal is generated from our low duty-cycle 40-GHz pulse source through optical time-division multiplexing.