Preface ........................................................ XI
List of Contributors ......................................... XIII
1 VECSEL Semiconductor Lasers: A Path to High-Power,
Quality Beam and UV to IR Wavelength by Design ............... 1
Mark Kuznetsov
1.1 Introduction ............................................ 1
1.2 What Are VECSEL Semiconductor Lasers .................... 2
1.2.1 History of VECSELs: Semiconductor Lasers,
Optical Pumping, and External Cavity ............. 2
1.2.2 Basic Principles of Operation: VECSEL Structure
and Function ..................................... 6
1.2.3 Basic Properties of VECSEL Lasers: Power
Scaling, Beam Quality, and Intracavity Optical
Elements ......................................... 9
1.2.3.1 Power Scaling ........................... 9
1.2.3.2 Beam Quality ........................... 10
1.2.3.3 Laser Functional Versatility Through
Intracavity Optical Elements ........... 11
1.2.4 VECSEL Wavelength Versatility Through
Materials and Nonlinear Optics .................. 12
1.2.4.1 Wavelength Versatility Through
Semiconductor Materials and
Structures ............................. 12
1.2.4.2 Wavelength Versatility Through
Nonlinear Optical Conversion ........... 14
1.3 How Do You Make a VECSEL Laser ......................... 16
1.3.1 Semiconductor Gain Medium and On-Chip Bragg
Mirror .......................................... 16
1.3.1.1 Semiconductor Gain Design for
VECSELs ................................ 16
1.3.1.2 On-Chip Multilayer Laser Bragg
Mirror ................................. 21
1.3.1.3 Semiconductor Wafer Structure .......... 22
1.3.2 Optical Cavity: Geometry, Mode Control, and
Intracavity Elements ............................ 24
1.3.3 Optical and Electrical Pumping .................. 29
1.3.4 VECSEL Laser Characterization ................... 33
1.4 Demonstrated Performance of VECSELs and Future
Directions ............................................. 38
1.4.1 Demonstrated Power Scaling and Wavelength
Coverage ........................................ 38
1.4.2 Commercial Applications ......................... 45
1.4.3 Current and Future Research Directions .......... 48
1.4.4 Future of VECSEL Lasers: Scalable Power with
Beam Quality from UV to IR ...................... 54
References .................................................. 57
2 Thermal Management, Structure Design, and Integration
Considerations for VECSELs .................................. 73
Stephane Calvez, Jennifer E. Hastie, Alan J. Kemp,
Nicolas Laurand, and Martin D. Dawson
2.1 Introduction ........................................... 73
2.2 VECSEL Structure Design ................................ 74
2.2.1 Material System Selection ....................... 74
2.2.2 Gain ............................................ 76
2.2.3 Mirrors ......................................... 79
2.2.4 Subcavity Designs ............................... 80
2.2.5 Growth .......................................... 81
2.2.6 Structure Characterization ...................... 82
2.2.7 Laser Cavity .................................... 83
2.3 Thermal Management ..................................... 84
2.3.1 Introduction: Why Is Thermal Management
Important? ...................................... 84
2.3.2 Thermal Management Strategies in VECSELs ........ 85
2.3.3 Modeling of Heat Flow in VECSELs: Guidelines .... 87
2.3.4 The Thin Device and Heat Spreader Approaches
at 1 and 2 μm ................................... 87
2.3.5 Important Parameters: The Thermal Conductivity
of the Mirror Structure, Submount, and Heat
Spreader ........................................ 89
2.3.6 Power Scaling of VECSELs ........................ 91
2.3.7 Wavelength Versatility .......................... 94
2.4 Laser Performance and Results .......................... 96
2.4.1 Power ........................................... 96
2.4.2 Efficiency ..................................... 100
2.4.3 Tuning ......................................... 103
2.5 Integration ........................................... 105
2.5.1 Microchip ...................................... 105
2.5.2 Pump Integration ............................... 107
2.5.3 Fiber-Tunable VECSELs .......................... 109
2.6 Conclusions ........................................... 111
References ............................................ 111
3 Red Semiconductor Disk Lasers by Intracavity Frequency
Conversion ................................................. 119
Oleg Okhotnikov and Mircea Guina
3.1 I ntroduction ......................................... 119
3.2 SDL with Frequency Doubling ........................... 121
3.2.1 General Principle of Frequency Doubling ........ 121
3.2.2 Power Scaling of SDLs .......................... 124
3.3 SDL Frequency Doubled to Red .......................... 126
3.3.1 Dilute Nitride Heterostructures for 1.2 μm
Light Emission ................................. 127
3.3.2 Plasma-Assisted MВЕ Growth of Dilute
Nitrides ....................................... 128
3.3.3 Design and Characteristics of Dilute Nitride
Gain Media ..................................... 130
3.3.4 Performance of 1220 nm SDL ..................... 133
3.3.5 SDL Intracavity Light Conversion to Red-
Orange ......................................... 136
3.4 Conclusions ........................................... 139
References ............................................ 139
4 Long-Wavelength GaSb Disk Lasers ........................... 143
Benno Rösener, Marcel Rattunde, John-Mark Hopkins,
David Burns, and Joachim Wagner
4.1 Introduction .......................................... 143
4.2 The Ш-Sb Material System .............................. 144
4.3 Epitaxial Layer Design and Growth of III-Sb Disk
Laser Structures ...................................... 146
4.3.1 Basic Structural Layout ........................ 147
4.3.2 Sample Growth and Post-Growth Analysis ......... 149
4.3.3 Epitaxial Design of In-Well-Pumped SDLs ........ 153
4.3.4 Sb-Based Active Regions on GaAs/AlGaAs DBRs .... 155
4.4 High-Power 2.X μm Disk Lasers ......................... 157
4.4.1 Initial Experiments ............................ 157
A.4.2 Sb-Based SDLs Using Intracavity Heat
Spreaders ...................................... 158
4.4.3 In-Well-Pumped Sb-Based Semiconductor Disk
Lasers ......................................... 163
4.4.4 Sb-Based Semiconductor Disk Lasers on GaAs
Substrates ..................................... 166
4.5 Tunable, Single-Frequency Lasers ...................... 167
4.5.1 Tunability ..................................... 168
4.5.2 Single-Frequency Operation ..................... 172
4.5.3 Experimental Results of a 2.3 μm Single-
Frequency SDL .................................. 176
4.6 Disk Lasers At and Above 3 μm Wavelength .............. 179
4.7 Conclusions ........................................... 179
References ............................................ 181
5 Semiconductor Disk Lasers Based on Quantum Dots ............ 187
Udo W. Pohl and Dieter Bimberg
5.1 Introduction .......................................... 187
5.2 Size Quantization in Optical Gain Media ............... 187
5.2.1 Quantum Dots in Lasers ......................... 189
5.2.2 Species of Quantum Dots ........................ 191
5.2.3 Energies of Confined Charge Carriers ........... 191
5.2.4 Quantum Dot Lasers ............................. 196
5.2.4.1 Edge-Emitting Quantum Dot Lasers ...... 196
5.2.4.2 Surface-Emitting Quantum Dot Lasers ... 198
5.3 Development of Disk Lasers Based on Quantum Dots ...... 200
5.3.1 Concepts of Gain Structures .................... 200
5.3.2 Adjustment of Quantum Dot Emission
Wavelength ..................................... 202
5.3.2.1 Tuning of Stranski-Krastanow Quantum
Dots .................................. 203
5.3.2.2 Tuning of Submonolayer Quantum Dots ... 204
5.3.3 Characteristics of Quantum Dot Disk Lasers ..... 205
5.3.3.1 Disk Lasers with Stranski-Krastanow
Quantum Dots .......................... 205
5.3.3.2 Disk Lasers with Submonolayer
Quantum Dots .......................... 207
5.4 Conclusions ........................................... 207
References ............................................ 208
6 Mode-Locked Semiconductor Disk Lasers ...................... 213
Thomas Südmeyer, Deran J.H.C Maas, and Ursula Keller
6.1 Introduction .......................................... 213
6.1.1 Ultrafast Lasers ............................... 213
6.1.2 Ultrafast Semiconductor Lasers ................. 215
6.1.3 Application Areas .............................. 216
6.2 SESAM Mode Locking of Semiconductor Disk Lasers ....... 219
6.2.1 Macroscopic Key Parameters of a SESAM .......... 220
6.2.1.1 Nonlinear Optical Reflectivity ........ 220
6.2.1.2 Temporal SESAM Response ............... 225
6.2.2 Pulse Formation ................................ 227
6.2.2.1 Model for the Pulse Shaping ........... 229
6.2.2.2 Mode-Locking Stability and the
Importance of Gain and SESAM
Saturation ............................ 231
6.2.2.3 Importance of Group Delay
Dispersion ............................ 232
6.2.3 SESAM Designs .................................. 233
6.2.3.1 SESAM Structure for Field
Enhancement Control ................... 233
6.2.3.2 Comparison of Quantum Well and
Quantum Dot SESAMs .................... 236
6.3 Mode Locking Results .................................. 239
6.3.1 Introduction ................................... 239
6.3.2 Mode-Locked VECSELs with High Average Output
Power .......................................... 240
6.3.2.1 Power Scaling of Mode-Locked
VECSELs ............................... 240
6.3.2.2 Experimental Results .................. 242
6.3.2.3 Outlook ............................... 243
6.3.3 VECSEL Mode Locking at High Repetition Rates ... 244
6.3.3.1 Mode Locking with Similar Area on
Gain and Absorber (1:1 Mode
Locking) .............................. 245
6.3.3.2 Mode-Locked VECSELs with up to 50
GHz ................................... 245
6.3.3.3 Outlook ............................... 246
6.3.4 Femtosecond Mode-Locked VECSELs ................ 246
6.3.4.1 Introduction .......................... 246
6.3.4.2 Mode Locking Results .................. 247
6.3.5 Electrically Pumped Mode-Locked VECSELs ........ 247
6.4 Mode-Locked Integrated External-Cavity Surface-
Emitting Laser (MIXSEL) ............................... 248
6.4.1 Introduction ................................... 248
6.4.2 Integration Challenges ......................... 249
6.4.3 Results ........................................ 251
6.4.4 Outlook ........................................ 252
6.5 Summary and Outlook ................................... 254
References ............................................ 256
7 External-Cavity Surface-Emitting Diode Lasers .............. 263
Aram Mooradian, Andrei Shchegrov, Ashish Tandon, and
Gideon Yoffe
7.1 Introduction .......................................... 263
7.2 Device Design and Performance ......................... 264
7.3 Mode Control, Cavity Design, and Thermal Lensing ...... 270
7.4 High-Power Arrays and Multielement Devices ............ 274
7.4.1 Design of the Chip ............................. 276
7.5 Carrier Dynamics ...................................... 286
7.5.1 Mode Locking ................................... 287
7.6 Nonlinear Optical Conversion with Surface-Emitting
Diode Lasers: Design and Performance .................. 287
7.6.1 Visible Laser Sources: Applications and
Requirements ................................... 287
7.6.2 Cavity Design Optimization and Trade-Offs for
Second Harmonic Generation with Surface-
Emitting Diode Lasers .......................... 289
7.6.3 Nonlinear Crystals Used in Intracavity
Frequency Conversion ........................... 291
7.6.4 Low-Noise, High Mode Quality, Continuous-
Wave Visible Laser Sources for
Instrumentation Applications ................... 294
7.6.5 Compact Visible Sources Scalable to Array
Architecture ................................... 297
References ................................................. 301
Index ......................................................... 305
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