Dynamics of III-V/SiN hybrid lasers with a dispersive narrow band mirror. stable single mode emission, self-mode locking regimes and tolerance to optical feedback. A theoretical study

Lorenzo Columbo

Direct, heterogeneous or hybrid integration of a new generation lasers sources in Silicon Photonics (SiPh) became very appealing for applications in the rapidly expanding fields of intra/inter chip data communications, sensing and LIDAR. Thanks to the great design flexibility of the SiPh platforms, lasers with long effective lengths have been realized to provide very narrow emission linewidth, wide tunability and high wall plug efficiency as required from applications. Nonetheless, very few works have been dedicated to the analysis of other related dynamical aspects such as the emerging in these configurations of multimode regimes and their resilience to spurious back reflections coming from the rest of the SiN circuit. To fill this gap we implemented a model based on a set of time-delayed algebraic equations able to describe the dynamics of an hybrid lasers based on III-V Reflective Semiconductor Optical Amplifier (RSOA) edge-coupled with a dispersive mirror realized with two high Q-micoring resonators on a SiN platform. We calculated the CW solutions by solving the oscillation condition and we studied their stability by using standard small signal analysis. These results highlight the important role played by the mirror bandwidth on the damping of the relaxation oscillations and the emergence of self-mode locked or chaotic regimes triggered by the competition among hybrid cavity modes. We addressed also the important issue related to the hybrid lasers tolerance to optical feedback and, very interestingly for isolator-free operation mode, we propose SiN mirror designs that should guarantee ultra-stable behaviour in presence of unwanted reflections. Finally, using a more rigorous time domain traveling wave approach, that correctly describes the RSOA gain/refractive index dependence from frequency and carriers density and accounts for electric field longitudinal propagation in RSOA, we were able to confirm the main results of the simplified model.

Lorenzo Columbo is a researcher at the Department of Electronics and Telecommunications, Politecnico di Torino. His current theoretical research activities mainly focuses on the study of nonlinear dynamics and self-organization phenomena (optical frequency combs and temporal solitons formation) in Quantum Dots lasers, Quantum Cascade Lasers and SiPh integrated lasers for applications in sensing, molecular spectroscopy and ICT.