en fr Modulation dynamics of InP-based quantum dot lasers and quantum cascade lasers Dynamique de modulation de lasers à îlots quantiques sur substrat InP et de lasers à cascade quantique Report as inadecuate




en fr Modulation dynamics of InP-based quantum dot lasers and quantum cascade lasers Dynamique de modulation de lasers à îlots quantiques sur substrat InP et de lasers à cascade quantique - Download this document for free, or read online. Document in PDF available to download.

1 FOTON - Fonctions Optiques pour les Technologies de l-informatiON

Abstract : High performance semiconductor lasers are strongly demanded in the rapidly increasing optical communication networks. Low dimensional nanostructure lasers are expected to be substitutes of their quantum well Qwell counterparts in the next-generation of energy-saving and high-bandwidth telecommunication optical links. Many efforts have been devoted during the past years to achieve nanostructure lasers with broad modulation bandwidth, low frequency chirp, and reduced linewidth enhancement factor. Particularly, 1.55-μm InP-based quantum dash Qdash-dot Qdot lasers are preferable for long-haul transmissions in contrast to the 1.3-μm laser sources. In this dissertation, we investigate the dynamic characteristics of InPbased nanostructure semiconductor lasers operating under direct current modulation, including the amplitude AM and frequency FM modulation responses, the linewidth enhancement factor also known as α-factor, as well as large-signal modulation responses. Using a semi-analytical analysis of the rate equation model, it is found that the modulation bandwidth of the quantum dot laser is strongly limited by the finite carrier capture and relaxation rates. In order to study the α- factor and chirp properties of the quantum dot laser, we develop an improved rate equation model, which takes into account the contribution of carrier populations in off-resonant states to the refractive index change. It is demonstrated that the α-factor of quantum dot lasers is strongly dependent on the pump current as well as the modulation frequency, in comparison to the case of Qwell lasers. The α-factor remains constant at low modulation frequencies



Author: Cheng Wang -

Source: https://hal.archives-ouvertes.fr/



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