Ultrafast Lasers Based on Quantum Dot Structures

In this monograph, the authors address the physics and engineering together with the latest achievements of efficient and compact ultrafast lasers based on novel quantum-dot structures and devices. Their approach encompasses a broad range of laser systems, while taking into consideration not only the physical and experimental aspects but also the much needed modeling tools, thus providing a holistic understanding of this hot topic.

Auteur

Eugene Avrutin has been working in the field of theory, numerical modelling, and computer-added design of semiconductor optoelectronic devices since 1986. Having previously been a researcher at the A.F. Ioffe Institute, St Petersburg (till 1993), and a research assistant in the University of Glasgow (1994-1999), he has held an academic position at the University of York since 2000. He has published two book chapters, more than 70 peer-reviewed journal papers and over a hundred conference papers, many of them in the field of fast and ultrafast laser sources and/or reduced dimensionality semiconductors.

Maria Ana Cataluna is a lecturer and a Royal Academy of Engineering/EPSRC Research Fellow at the University of Dundee (UK). She has been committed to research in ultrafast laser physics and technology development since 2000, having previously worked at the Instituto Superior Técnico, Portugal (2000-2002), at the University of St. Andrews, UK (2003-2007), subsequently joining the University of Dundee in 2007. She was awarded the IEEE Photonics Society Graduate Student Fellowship (2007), for her work on innovative mode-locking regimes in ultrafast quantum-dot based lasers. She has published more than 50 papers in peer-reviewed journals and conference proceedings and three invited book chapters.

Edik Rafailov has been engaged in the research and development of high-power cw and ultrashort pulse lasers, nonlinear and integrated optics since 1987. In 2005 he moved to Dundee University as a lecturer and established a new Photonics and Nanoscience group. In 2008 he became a reader and two years later a professor. He was previously a senior researcher at Ioffe Institute, St Petersburg (1987-1997) and a research fellow at the University of St. Andrews (1997-2005). He has authored and co-authored over 220 articles in refereed journals and conference proceedings, three invited chapters and numerous invited talks to CLEO, SPIE and LEOS. He also holds 8 UK and two US patents. Professor Rafailov is the coordinator of projects funded by EU FP7 program and EPSRC. His current research interests include novel high-power CW, short, ultrashort-pulse and high-repetition rate lasers; generation of UV/visible/IR and THz radiation, nano-structures; nonlinear optics and Biophotonics.

Contenu

Introduction IX

Acknowledgments XI

1 Semiconductor Quantum Dots for Ultrafast Optoelectronics 1

1.1 The Role of Dimensionality in Semiconductor Materials 1

1.2 Material Systems Used 4

1.2.1 IIIV Epitaxially Grown Quantum Dots 4

1.2.2 QD-Doped Glasses 6

1.2.3 Quantum Dashes 6

1.3 Quantum Dots: Distinctive Properties for Ultrafast Devices 7

1.3.1 Inhomogeneous Broadening 7

1.3.2 Ultrafast Carrier Dynamics 9

2 Foundations of Quantum Dot Theory 11

2.1 Energy Structure and Matrix Elements 11

2.2 Theoretical Approaches to Calculating Absorption and Gain in Quantum Dots 14

2.3 Kinetic Theory of Quantum Dots 22

2.4 LightMatter Interactions in Quantum Dots 37

2.5 The Nonlinearity Coefficient 51

3 Quantum Dots in Amplifiers of Ultrashort Pulses 55

3.1 Optical Amplifiers for High-Speed Applications: Requirements and Problems 55

3.2 Quantum Dot Optical Amplifiers: Short-Pulse Operating Regime 62

3.3 Quantum Dot Optical Amplifiers at High Bit Rates: Low Distortions and Patterning-Free Operation 63

3.4 Nonlinear Operation and Limiting Function Using QD Optical Amplifiers 76

4 Quantum Dot Saturable Absorbers 77

4.1 Foundations of Saturable Absorber Operation 77

4.2 The General Physical Principles of Saturable Absorption in Semiconductors 80

4.2.1 Physical Processes in a Saturable Absorber 80

4.2.2 Geometry of Saturable Absorber: SESAM versus Waveguide Absorber The Cavity Enhancement of Saturable Absorption and the Standing Wave Factor in SESAMs 84

4.3 The Main Special Features of a Quantum Dot Saturable Absorber Operation 87

4.3.1 Bandwidth of QD SAs 88

4.3.2 Dynamics of Carrier Relaxation: Ultrafast Recovery of Absorption 88

4.3.3 Saturation Fluence 94

5 Monolithic Quantum Dot Mode-Locked Lasers 99

5.1 Introduction to Semiconductor Mode-Locked Lasers 99

5.1.1 Place of Semiconductor Mode-Locked Lasers Among Other Ultrashort Pulse Sources 99

5.1.2 Mode-Locking Techniques in Laser Diodes: The Main Principles 100

5.1.3 Passive Mode Locking: The Qualitative Picture, Physics, and Devices 101

5.2 Theoretical Models of Mode Locking in Semiconductor Lasers 103

5.2.1 Small-Signal Time Domain Models: Self-Consistent Pulse Profile 103

5.2.2 Large-Signal Time Domain Approach: Delay Differential Equations Model 109

5.2.3 Traveling Wave Models 120

5.2.4 Frequency and TimeFrequency Treatment of Mode Locking: Dynamic Modal Analysis 125

5.3 Main Predictions of Generic Mode-Locked Laser Models and their Implication for Quantum Dot Lasers 126

5.3.1 Laser Performance Depending on the Operating Point 126

5.3.2 Main Parameters that Affect Mode-Locked Laser Behavior 129

5.4 Specific Features of Quantum Dot Mode-Locked Lasers in Theory and Modeling 131

5.4.1 Delay Differential Equation Model for Quantum Dot Mode-Locked Lasers 132

5.4.2 Traveling Wave Modeling of Quantum Dot Mode-Locked Lasers: Effects of Multiple Levels and Inhomogeneous Broadening 141

5.4.3 Modal Analysis for QD Mode-Locked Lasers 153

5.5 Advantages of Quantum Dot Materials in Mode-Locked Laser Diodes 154

5.5.1 Advantages of QD Saturable Absorbers 154

5.5.2 Broad Gain Bandwidth 154

5.5.3 Low Threshold Current 155

5.5.4 Low Temperature Sensitivity 155

5.5.5 Suppressed Carrier Diffusion 156

5.5.6 Lower Level of Amplified Spontaneous Emission 157

5.5.7 Linewidth Enhancement Factor 157

5.6 Ultrashort Pulse Generation: Achievements and Strategies 158

5.6.1 Monolithic Mode-Locked Quantum Dot Lasers 158

5.6.2 Chirp Measurement and Pulse Compression 161

5.6.3 Toward Higher Power: Tapered Lasers 164

5.6.4 Toward Higher Repetition Rates 165

5.6.5 External Cavity QD Mode-Locked Lasers 166

5.7 Noise Characteristics of QD Mode-Locked Lasers 167

5.7.1 Timing Jitter 167 5.7.2 Pulse Repetiti...