Long-Term Frequency Stabilization of 10-GHz Quantum-Dash Passively Mode-Locked Lasers

This paper reports on the repetition frequency stability of InAs/InP quantum-dash-based mode locked lasers emitting in the 1.55-μm telecom window and of a long-term frequency stabilization schemes. We discuss the main noise sources that affect the frequency stability. In free running operation, quantum-dash-based mode locked lasers demonstrate an initial long-term stability of ~ 10-7. In order to improve it, we developed different approaches based on electrical feedback and optical feedback loops. The stabilization systems exploit the bias-dependent frequency drift and the optical feedback sensitivity to keep repetition frequency in lock for an extensive period of time with a stability of 1.5 × 10^-9.