| Rafailov E.U. Ultrafast lasers based on quantum dot structures: physics and devices / E.U.Railov, M.A.Cataluna, E.A.Avrutin. - Weinheim: Wiley-VCH, 2011. - xi, 250 p.: ill. - Ref.: p.223-239. - Ind.: p.242-250. - ISBN 978-3-527-40928-0
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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 III-V 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 Light-Matter 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 Time-Frequency 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
5.5.5 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 ...... 258
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 Repetition Rate Stability and
Resilience to Optical Feedback ................. 170
5.7.3 Performance Under Optical Injection ............ 172
5.8 Performance of QD Mode-Locked Lasers at Elevated
Temperature ........................................... 174
5.8.1 Stable Mode Locking at Elevated Temperature .... 174
5.8.2 Pulse Duration Trends at Higher Temperatures ... 175
5.8.3 The Use of p-Doping in QD Mode-Locked Lasers ... 176
5.9 Exploiting Different Transitions for Pulse
Generation ............................................ 176
5.9.1 Mode Locking via Ground and Excited States ..... 176
5.9.2 The Excited-State Transition as Tool for
Novel Mode-Locking Regimes ..................... 179
5.10 Summary and Outlook ................................... 180
5.10.1 QD Mode-Locked Laser Diodes: New
Functionalities ................................ 180
5.10.2 Future Directions .............................. 181
6 Ultrashort Pulse Solid State Lasers Based on Quantum
Dot Saturable Absorbers .................................... 183
6.1 A Brief Historical Overview of Ultrashort-Pulse
Generation ............................................ 183
6.2 Macroscopic Parameters of Saturable Absorbers ......... 184
6.3 QD SESAMs for Efficient Passive Mode Locking of
Solid-State Lasers Emitted around 1 μm ................ 187
6.4 QD SESAMs for Efficient Passive Mode Locking of
Solid-State Lasers Emitted around 1.3 μm .............. 193
6.5 QD SESAMs for the Passive Mode Locking of Fiber
Lasers ................................................ 199
6.6 Mode-Locked Semiconductor Disk Lasers Incorporating
QD SESAMs ............................................. 201
6.7 Optically Pumped Quantum Dot VECSELs .................. 204
7 Saturable Absorbers Based on QD-Doped Classes .............. 207
7.1 II—VI Semiconductor Nanocrystals in Glass ............. 207
7.2 IV-VI Semiconductor QD-Doped Glasses for Ultrashort-
Pulse Generation from Solid-State Lasers .............. 209
7.3 QD-Doped Glass Saturable Absorbers for Passive Mode
Locking around 1.3 μm ................................. 210
7.4 Cr:YAG Laser Passively Mode Locked with a QD-Doped
Glass Saturable Absorber .............................. 212
7.5 PbS QD-Doped Glass Saturable Absorbers for Passive
Mode Locking around 1 μm and Their Nonlinear
Characteristics ....................................... 214
8 Emerging Applications of Ultrafast Quantum Dot Lasers ...... 217
8.1 Optical Communications ................................ 217
8.2 Datacoms .............................................. 219
8.3 Biophotonics and Medical Applications ................. 220
8.4 Outlook ............................................... 220
References ................................................. 223
Index ...................................................... 241
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