Nonlinear Dynamics in Semiconductor Lasers 2023 - Abstract
Gurevich, Svetlana
We analyze the dynamics of passive mode-locking in Vertical External-Cavity Surface-Emitting Lasers using a first- principles dynamical model based on delay algebraic equations that intrinsically contain the group velocity dispersion incurred by the micro-cavities. We show that apart from the conventional fundamental mode- locked state, another mode-locked solution with higher amplitude exists that we termed as “super mode- locking”. We show that this regime exists for a specific detuning between the gain and the saturable absorber micro-cavities. Using a combination of multi-scale analysis, path-continuation and direct numerical simulations, we disclose the mechanisms responsible for the emergence and stability of the super mode-locked state. In particular, we find that due to the relative detuning between the maximum of gain and the peak of absorption, our theoretical approach reproduces naturally the presence of either positive or a negative second order group velocity dispersion. This result allows us to explain why super mode-locking appears only for the anomalous second order dispersion regime. Further, we derive a normal form partial differential equation close to the onset of lasing using a multiple time scale analysis. We show that our model differs in several aspects with the generic Haus master equation and that it shows a good agreement with direct numerical simulations of the original delay algebraic model.