80-GHz pulse generation from a repetition-rate-doubled FM mode-locking fiber laser

We demonstrated a simple method to realize repetition-rate-doubling in a frequency modulation (FM) mode-locking fiber laser. The mode-locking of the laser is based on converting FM modulation to amplitude modulation by using a phase-modulated optical fiber loop mirror, which is formed by a phase modulator and an additional coupler only. With 40-GHz modulation, we obtained 80-GHz 1.74-ps transform-limited pulse train in the experiments.