Dynamics Of Quantum Dot Lasers

This thesis deals with the dynamics of state-of-the-art nanophotonic semiconductor structures, providing essential information on fundamental aspects of nonlinear dynamical systems on the one hand, and technological applications in modern telecommunication on the other. Three different complex laser structures are considered in detail: (i) a quantum-dot-based semiconductor laser under optical injection from a master laser, (ii) a quantum-dot laser with optical feedback from an external resonator, and (iii) a passively mode-locked quantum-well semiconductor laser with saturable absorber under optical feedback from an external resonator. Using a broad spectrum of methods, both numerical and analytical, this work achieves new fundamental insights into the interplay of microscopically based nonlinear laser dynamics and optical perturbations by delayed feedback and injection.

A distinctive discussion of the nonlinear dynamical phenomena of semiconductor lasers. The book combines recent results of quantum dot laser modeling with mathematical details and an analytic understanding of nonlinear phenomena in semiconductor lasers and points out possible applications of lasers in cryptography and chaos control. This interdisciplinary approach makes it a unique and powerful source of knowledge for anyone intending to contribute to this field of research. By presenting both experimental and theoretical results, the distinguished authors consider solitary lasers with nano-structured material, as well as integrated devices with complex feedback sections. In so doing, they address such topics as the bifurcation theory of systems with time delay, analysis of chaotic dynamics, and the modeling of quantum transport. They also address chaos-based cryptography as an example of the technical application of highly nonlinear laser systems.

This thesis sheds light on the unique dynamics of optoelectronic devices based on semiconductor quantum-dots. The complex scattering processes involved in filling the optically active quantum-dot states and the presence of charge-carrier nonequilibrium conditions are identified as sources for the distinct dynamical behavior of quantum-dot based devices. Comprehensive theoretical models, which allow for an accurate description of such devices, are presented and applied to recent experimental observations. The low sensitivity of quantum-dot lasers to optical perturbations is directly attributed to their unique charge-carrier dynamics and amplitude-phase-coupling, which is found not to be accurately described by conventional approaches. The potential of quantum-dot semiconductor optical amplifiers for novel applications such as simultaneous multi-state amplification, ultra-wide wavelength conversion, and coherent pulse shaping is investigated. The scattering mechanisms and the unique electronic structure of semiconductor quantum-dots are found to make such devices prime candidates for the implementation of next-generation optoelectronic applications, which could significantly simplify optical telecommunication networks and open up novel high-speed data transmission schemes.

A distinctive discussion of the nonlinear dynamical phenomena of semiconductor lasers. The book combines recent results of quantum dot laser modeling with mathematical details and an analytic understanding of nonlinear phenomena in semiconductor lasers and points out possible applications of lasers in cryptography and chaos control. This interdisciplinary approach makes it a unique and powerful source of knowledge for anyone intending to contribute to this field of research. By presenting both experimental and theoretical results, the distinguished authors consider solitary lasers with nano-structured material, as well as integrated devices with complex feedback sections. In so doing, they address such topics as the bifurcation theory of systems with time delay, analysis of chaotic dynamics, and the modeling of quantum transport. They also address chaos-based cryptography as an example of the technical application of highly nonlinear laser systems.

André Röhm investigates the dynamic properties of two-state lasing quantum dot lasers, with a focus on ground state quenching. With a novel semi-analytical approach, different quenching mechanisms are discussed in an unified framework and verified with numerical simulations. The known results and experimental findings are reproduced and parameter dependencies are systematically studied. Additionally, the turn-on dynamics and modulation response curves of two-state lasing devices are presented.

1. Introduction to photonic quantum dot nanomaterials and devices. 1.1. Physical properties of quantum dots. 1.2. Active semiconductor gain media. 1.3. Quantum dot lasers. 1.4. Laser cavities -- 2. Theory of quantum dot light-matter dynamics. 2.1. Rate equations. 2.2. Maxwell-Bloch equations. 2.3. Quantum luminescence equations. 2.4. Quantum theoretical description -- 3. Light meets matter I: microscopic carrier effect. 3.1. Dynamics in the active charge carrier plasma. 3.2. Dynamic level hole burning. 3.3. Ultrashort nonlinear gain and index dynamics. 3.4. Conclusion -- 4. Light meets matter II: mesoscopic space-time dynamics. 4.1. Introduction: transverse and longitudinal mode dynamics. 4.2. Influence of the transverse degree of freedom and nano-structuring on nearfield dynamics and spectra. 4.3. Longitudinal modes. 4.4. Coupled space-time dynamics. 4.5. Conclusion -- 5. Performance and characterisation: properties on large time and length scales. 5.1. Introduction. 5.2. Spatial and spectral beam quality. 5.3. Dynamic amplitude phase coupling. 5.4. Conclusion -- 6. Nonlinear pulse propagation in semiconductor quantum dot lasers. 6.1. Dynamic shaping of short optical pulses. 6.2. Nonlinear femtosecond dynamics. 6.3. Conclusion -- 7. High-speed dynamics. 7.1. Mode-locking in multi-section quantum dot lasers. 7.2. Dependence of pulse duration on injection current, bias voltage and device geometry. 7.3. Radio frequency spectra of the emitted light. 7.4. Short-pulse optimisation. 7.5. Conclusion -- 8. Quantum dot random lasers. 8.1. Spatially inhomogeneous semiconductor quantum dot ensembles. 8.2. Coherence properties. 8.3. Random lasing in semiconductor quantum dot ensembles. 8.4. Conclusion -- 9. Coherence properties of quantum dot micro-cavity lasers. 9.1. Introduction. 9.2. Radial signal propagation and coherence trapping. 9.3. Influence of disorder. 9.4. Conclusions

Presents fundamental theories and simulations of the spatio-temporal dynamics and quantum fluctuations in semiconductor lasers. The dynamic interplay of light and matter is theoretically described by taking into account microscopic carrier dynamics, spatially dependent light-field propagation and the influence of spontaneous emission and noise.