Wavelength-tunable high-repetition-rate pulse generation in a SOA-based fiber laser with gain instability

Introducing negative optical feedback into a semiconductor optical amplifier-based laser presents a straightforward and effective approach for generating high-repetition-rate pulses through the mechanism of self-sustaining cross-gain modulation. In this work, we demonstrate, for the first time, the tunability of high-frequency pulse generation over a wide wavelength range by adjusting the central transmission wavelength of a tunable filter. Our laser system achieved a full tuning range from 1480 nm to 1556 nm (76 nm) while maintaining pulsed lasing. Remarkably, the laser exhibited a maximum pulse contrast exceeding 85% over a tuning range of 43 nm, from 1505.7 nm to 1548.7 nm. At any wavelength within this range, stable, self-starting pulse generation was consistently achieved, with a pulse repetition rate of 1.3 GHz.