On-Chip Multiple Colliding Pulse Mode-Locked Semiconductor Laser

We report for the first time to the best of our knowledge, an on-chip multiple colliding pulse mode-locked semiconductor laser source. The device structure is fully integrated, replacing cleaved facet mirrors by using multimode interference reflectors; this allows us to precisely control the location of the saturable absorbers within the cavity length, which is critical to achieve the multiple colliding regime. In this paper, we succeeded to achieve this regime generating a repetition rate at four times the fundamental round-trip frequency, demonstrating a repetition rate within the millimeter wave frequency range, at 100 GHz using a 25 GHz resonator cavity length. We also demonstrate the advantage of having the signal on-chip including a boost semiconductor optical amplifier in order to increase the output optical power. This novel structure was fabricated on a generic InP photonic integrated technology through a multi-project wafer run.