Modeling Passive Mode-Locking in Quantum Dot lasers: a comparison between a Finite Difference Travelling Wave model and a Delayed Differential Equation approach

We present a detailed quantitative comparison between a finite-difference traveling wave (FDTW) model and a delayed differential equation (DDE) approach for the simulation of passive mode-locking in quantum dot lasers with both ring and Fabry-Perot (FP) cavities. Modifications with respect to the standard DDE models available in the literature are proposed. The new DDE approach improves the quantitative agreement with the FDTW model when applied to the simulation of passive mode-locking in FP lasers, preserving a very high computational efficiency. The modifications proposed in the DDE model also apply to the simulation of quantum-well and bulk devices.