2006, Viktorov, Evgeny, Mandel, Paul, Vladimirov, Andrei, Bandelow, Uwe

We propose a model for passive mode-locking in quantum dot laser and report on specific dynamical properties of the regime which is characterized by a fast gain recovery. No Q-switching instability has been found accompanying the mode-locking. Bistability can occur between the mode-locking regime and zero intensity steady state.

2010, Radziunas, Mindaugas, Vladimirov, Andrei G., Viktorov, Evgeny A., Fiol, Gerrit, Schmeckebier, Holger, Birnmberg, Dieter

We describe the formation of a strong pulse asymmetry in mode-locked quantum-dot edge-emitting two-section semiconductor lasers. A mode decomposition technique reveals the role of the superposition of different modal groups. The results of theoretical analysis are supported by experimental data.

2010, Suwanpinij, Piyada, Togobytska, Nataliya, Prahl, Ulrich, Weiss, Wolf, Hömberg, Dietmar, Bleck, Wolfgang

In this article, the Mo-Mn dual phase steel and its process parameters in hot rolling are discussed. The process window was derived by combining the experimental work in a hot deformation dilatometer and numerical calculation of process parameters using rate law models for ferrite and martensite transformation. The ferrite formation model is based on the Leblond and Devaux approach while martensite formation is based on the Koistinen-Marburger (K-M) formula. The carbon enrichment during ferrite formation is taken into account for the following martensite formation. After the completion of the parameter identification for the rate law model, the evolution of phases in multiphase steel can be addressed. Particularly, the simulations allow for predicting the preferable degree of retained strain and holding temperature on the run out table (ROT) for the required ferrite fraction.

2008, Vladimirov, Andrei, Pimenov, Alexander, Rachinskii, Dmitrii

Bifurcation mechanisms of the development and break up of different operation regimes in a passively mode-locked monolithic semiconductor laser are studied by solving numerically partial differential equations for amplitudes of two counterpropagating waves and carrier densities in gain and absorber sections. It is shown that harmonic mode-locking regime with two pulses in the cavity can exhibit a period-doubling bifurcation leading to different amplitudes and separations of the pulses. The effect of linewidth enhancement factors in gain and absorber sections on the laser dynamics is discussed.

2010, Radziunas, Mindaugas, Vladimirov, A.G., Viktorov, E.A.

We analyze the dynamics of a mode-locked quantum-dot edge-emitting semiconductor laser consisting of reversely biased saturable absorber and forward biased amplifying sections. To describe spatial non-uniformity of laser parameters, optical fields and carrier distributions we use the traveling wave model, which takes into account carrier exchange processes between wetting layer and quantum dots. A comprehensive parameter study and an optical mode analysis of operation regimes are presented.

2006, Hüttl, Bernd

Inherent Q-switching as a source of intra-cavity pulse energy modulations, i.e. unwanted amplitude noise, is still a challenging task in order to fabricate monolithic mode-locked semiconductor lasers in view of different commercial applications. In this paper, the results of experimental investigations on the influence of the quantum well number on the occurrence and suppression of Q-switching in 40 GHz mode-locked multiple quantum well buried heterostructure lasers are presented. Improved mode-locked lasers emit short optical pulses (<=1.6 ps) with very low amplitude noise (1-2%) and timing jitter (50-100 fs).