In this paper, a theoretical model is used to investigate the lasing spectrum properties of InAs-InP(113)B quantum dot (QD) lasers emitting at 1.55 m. The numerical model is based on a multipopulation rate equations analysis. Calculations take into account the QD size dispersion as well as the temperature dependence through both the inhomogeneous and the homogeneous broadenings. This paper demonstrates that the model is capable of reproducing the spectral behavior of InAs-InP QD lasers. Especially, this study aims to highlight the transition of the lasing wavelength from the ground state (GS) to the excited state (ES). In order to understand how the QD laser turns on, calculated optical spectra are determined for different cavity lengths and compared to experimental ones. Unlike InAs-GaAs QD lasers emitting at 1.3 m, it is shown that a continuous transition from the GS to the ES is exhibited because of the large inhomogeneous broadening comparable to the GS and ES lasing energy difference. Index Terms-Quantum dot (QD), rate equation, semiconductor laser. I. INTRODUCTION L OW-COST, directly modulated lasers will play a major role in the next generation telecommunication links (local and metropolitan area network) for uncooled and isolator-free applications. As a consequence, semiconductor lasers based on low-dimensional heterostructures such as quantum dot (QD) laser are very promising. Indeed, QD structures have attracted a lot of attention in the last decade since they exhibit many interesting and useful properties such as low threshold current [1],

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In this paper, a theoretical model is used to investigate the lasing spectrum properties of InAs/InP (113)B quantum dot (QD) lasers emitting at 1.55 µm. The numerical model used is based on a multi-population rate equation (MPRE) analysis. It takes into account the effect of the competition between the inhomogeneous broadening (due to the QD size dispersion) and the homogenous broadening as well as a nonlinear gain variation associated to a multimode laser emission. The double laser emission and the temperature dependence of lasing spectra of self-assembled InAs/InP quantum dot lasers is studied both experimentally and theoretically.

Numerical models based on rate equations are used to study carrier dynamics in the two lowest energy levels of an InAs/InP (113)B quantum dot (QD) system. Two different theories are presented, one based on a cascade-relaxation model and the other using an additional efficient carrier relaxation. The comparison between these two theoretical approaches leads to a qualitative understanding of the origin of the two-state lasing in 1.55 mm InAs/InP (113)B (QD) lasers. In order to investigate the QD laser dynamics, numerical results for the turn-on delay of the double laser emission are also presented and discussed.

Thanks to optimized growth techniques, a high density of uniformly sized InAs quantum dots (QD) can be grown on InP(113)B substrates. Low threshold currents obtained at 1.54 μm for broad area lasers are promising for the future. This paper is a review of the recent progress toward the understanding of electronic properties, carrier dynamics and device modelling in this system, taking into account materials and nanostructures properties. A first complete analysis of the carrier dynamics is done by combining time-resolved photoluminescence experiments and a dynamic three-level model, for the QD ground state (GS), the QD excited state (ES) and the wetting layer/barrier (WL). Auger coefficients for the intradot assisted relaxation are determined. GS saturation is also introduced. The observed double laser emission for a particular cavity length is explained by adding photon populations in the cavity with ES and GS resonant energies. Direct carrier injection from the WL to the GS related to the weak carrier confinement in the QD is evidenced. In a final step, this model is extended to QD GS and ES inhomogeneous broadening by adding multipopulation rate equations (MPREM). The model is now able to reproduce the spectral behavior in InAs-InP QD lasers. The almost continuous transition from the GS to the ES as a function of cavity length is then attributed to the large QD GS inhomogeneous broadening comparable to the GS-ES lasing energy difference. Gain compression and Auger effects on the GS transition are also be discussed.