Nanosecond-Scale Discrete Wavelength Switching in Feedback-Controlled Single-Gain-Section Multi-Wavelength Lasers

We investigate discrete wavelength switching in single-gain-section multi-wavelength lasers monolithically integrated on InP with phase-controlled optical-feedback. By modulating the feedback phase, nanosecond-scale wavelength switching is experimentally demonstrated with transition times below 2.5 ns. Measurements consistently show that the switching time decreases with stronger optical feedback and larger phase-modulation amplitudes. Transitions from lower to higher modal gain are faster. We support the experimental observations with a multi-mode extension of the Lang-Kobayashi rate-equation model. We analyze the influence of laser, feedback-cavity, and modulation parameters on the switching dynamics, and highlight the role of mode coupling. These results highlight the potential of integrated multi-wavelength lasers for compact and high-speed all-optical networking systems.