Generation and Propagation of Bound-State Pulses in a Passively Mode-Locked Figure-Eight Laser

We have investigated the generation and propagation of robust bound-state pulses emitted from a passively mode-locked figure-eight laser with net-anomalous dispersion. Two pulses with the pulse duration of 1.3 ps and the separation of 2.2 ps exhibit a strongly modulated spectral profile. The experimental observations show that the pulse duration and the separation increase approximately linearly along the extracavity single-mode fiber (SMF). The pulse duration and separation are broadened by a factor of 7 and 5.7, respectively, after the pulse pair propagates through the standard SMF of 202 m. The theoretical results well agree with the experimental observations.