Optical Frequency Comb (OFC) generated by semiconductor lasers are currently widely used in the extremely timely field of high capacity optical interconnects and high precision spectroscopy. In the last decade, several experimental evidences of spontaneous OFC generation have been reported in single section Quantum Dot (QD) lasers. Here we provide a physical understanding of these self-organization phenomena by simulating the multi-mode dynamics of a single section Fabry-Perot (FP) QD laser using a Time-Domain Traveling-Wave (TDTW) model that properly accounts for coherent radiation-matter interaction in the semiconductor active medium and includes the carrier grating generated by the optical standing wave pattern in the laser cavity. We show that the latter is the fundamental physical effect at the origin of the multi-mode spectrum appearing just above threshold. A self-mode-locking regime associated with the emission of OFC is achieved for higher bias currents and ascribed to nonlinear phase sensitive effects as Four Wave Mixing (FWM). Our results explain in detail the behaviour observed experimentally by different research groups and in different QD and Quantum Dash (QDash) devices.

We present a time-domain travelling-wave model for the simulation of passive mode-locking in quantum dot (QD) lasers; accurate expressions for the time varying QD optical susceptibility and the QD spontaneous emission noise source are introduced in the 1-D wave equations and numerically described using a set of infinite-impulse response filters. The inhomogeneous broadening of the density of states of the whole QD ensemble as well as the homogeneous linewidth of each QD interband transition are properly taken into account in the model. Population dynamics in the QD, quantum well, and barrier states under both forward and reverse bias conditions are modeled via proper sets of multi-population rate equations coupled with the field propagation equations. The model is first applied to the study of gain and absorption recovery in a QD semiconductor optical amplifier under both forward and reverse bias conditions. Simulations of passive mode-locking in a two-section QD laser are then performed as a function of the bias parameters. Gain and absorption dynamics leading to the generation of mode-locking pulses is described. The onset of a trailing-edge instability at low currents is observed and fully explained in the framework of the described model.

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.

This paper presents a systematic investigation on the exploitation of the modulation bandwidth enhancement that can be obtained using the photon-photon resonance (PPR) effects in distributed Bragg reflector (DBR) lasers with antireflection coating at the grating end facet. For the first time, to the best of our knowledge, a complete design procedure has been found that allows a precise positioning of the PPR frequency; such a procedure has been successfully validated both in small and large signal modulation regimes. Conditions for maximum bit rate transmission are also discussed and verified analyzing the eye diagrams obtained by numerical simulations.

In this paper, we investigate with numerical simulations the rich multimode dynamics of quantum dot Fabry-Perot lasers. We have used a time-domain traveling-wave approach including the electron and hole carrier dynamics in the various quantum dot confined states, the inhomogeneous broadening of the complex gain spectrum, the polarization dynamics, and the effect of the carrier-photon interaction in the cavity. The role of the various nonlinear interaction mechanism on the broadening of optical spectrum of the quantum dot laser has been investigated, and the main parameters responsible for the phase locking between the longitudinal modes have been identified. We show that in some cases, it is possible to obtain pulses after simulating the propagation of the laser output field in a dispersive medium. Many of the obtained simulation results are in good agreement with the experiments reported in the literature.

We report on the development of a new generation of high-power ultrashort pulse quantum-dot lasers with tapered gain section. Two device designs are proposed and fabricated, with different total...