Compact Semiconductor Lasers

This book brings together in a single volume a unique contribution by top experts from around the world in the field of compact semiconductor lasers in order to provide a comprehensive description and analysis of the current status as well as future directions in the field of micro– and nano–scale semiconductor lasers. It is organized according to the various forms of micro– or nano–laser cavity configuration with each chapter discussing key technical issues, including semiconductor carrier recombination processes and optical gain dynamics, photonic confinement behavior and output coupling mechanisms, carrier transport considerations relevant to the injection process– and emission mode control. From the contents: • Nano–scale metallo–dielectric coherent light sources • Optically pumped semiconductor photonic crystal lasers • Electrically pumped photonic crystal lasers: laser diodes and quantum cascade lasers • Photonic crystal VCSELs • III– V compact lasers integrated onto silicon (SOI) • Semiconductor micro–ring lasers • Nonlinearity in Semiconductor micro–ring lasers

Preface and Introduction XIII List of Contributors XXI Color Plates XXV 1 Nanoscale Metallo–Dielectric Coherent Light Sources 1 Maziar P. Nezhad, Aleksandar Simic, Amit Mizrahi, Jin–Hyoung Lee, Michael Kats, Olesya Bondarenko, Qing Gu, Vitaliy Lomakin, Boris Slutsky, and Yeshaiahu Fainman 1.1 Introduction 1 1.2 Composite Metallo–Dielectric–Gain Resonators 4 1.2.1 Composite Gain–Dielectric–Metal Waveguides 5 1.2.2 Composite Gain–Dielectric–Metal 3D Resonators 7 1.3 Experimental Validations of Subwavelength Metallo–Dielectric Lasers for Operation at Room–Temperature 9 1.3.1 Fabrication Processes for Subwavelength Metallo–Dielectric Lasers 10 1.3.2 Characterization and Testing of Subwavelength Metallo–Dielectric Lasers 11 1.4 Electrically Pumped Subwavelength Metallo–Dielectric Lasers 13 1.4.1 Cavity Design and Modeling of Electrically Pumped Subwavelength Metallo–Dielectric Lasers 13 1.4.2 Fabrication of Electrically Pumped Subwavelength Metallo–Dielectric Lasers 17 1.4.3 Measurements and Discussion of Electrically Pumped Subwavelength Metallo–Dielectric Lasers 18 1.5 Thresholdless Nanoscale Coaxial Lasers 20 1.5.1 Design and Fabrication of Thresholdless Nanoscale Coaxial Lasers 22 1.5.2 Characterization and Discussion of Thresholdless Nanoscale Coaxial Lasers 23 1.6 Summary, Discussions, and Conclusions 27 Acknowledgments 29 References 29 2 Optically Pumped Semiconductor Photonic Crystal Lasers 33 Fabrice Raineri, Alexandre Bazin, and Rama Raj 2.1 Introduction 33 2.2 Photonic Crystal Lasers: Design and Fabrication 35 2.2.1 Micro/Nano Cavity Based PhC Lasers 36 2.2.1.1 Lasers Based on 2D PhC Cavities 36 2.2.1.2 Lasers Based on 3D PhC Cavities 44 2.2.2 Slow–Light Based PhC Lasers: DFB–Like Lasers 46 2.2.2.1 2D PhC DFB–Like Lasers for In–Plane Emission 47 2.2.2.2 2D PhC DFB– Like Lasers for Surface Emission 50 2.3 Photonic Crystal Laser Characteristics 52 2.3.1 Rate Equation Model and PhC Laser Parameters 52 2.3.1.1 Linear Rate Equation Model 52 2.3.1.2 PhC Laser Parameters 53 2.3.2 The Stationary Regime in PhC Lasers 55 2.3.3 Dynamics of PhC Lasers 60 2.4 The Final Assault: Issues That Have Been Partially Solved and Others That Remain to Be Solved Before Photonic Crystal Lasers Become Ready for Application 65 2.4.1 Room Temperature Continuous Wave Room Temperature Operation of Photonic Crystal Nano–Lasers 66 2.4.1.1 CW Operation via Nonradiative Recombination Reduction 66 2.4.1.2 CW Operation via Increased Heat Sinking 69 2.4.2 Interfacing and Power Issues 74 2.4.2.1 Interfacing an Isolated PhC Cavity–Based Device with the External World 74 2.4.2.2 Interfacing Active–PhC Cavity–Based Devices within an Optical Circuit 77 2.5 Conclusions 82 References 83 3 Electrically Pumped Photonic Crystal Lasers: Laser Diodes and Quantum Cascade Lasers 91 Xavier Checoury, Raffaele Colombelli, and Jean–Michel Lourtioz 3.1 Introduction 91 3.2 Near–Infrared and Visible Laser Diodes 93 3.2.1 Photonic Crystal Microcavity Lasers 93 3.2.1.1 Photonic Crystals in Suspended (or Sustained) Membrane 93 3.2.1.2 Other Promising Designs 96 3.2.2 Waveguide Lasers in the Substrate Approach: Weak Vertical Confinement 98 3.2.2.1 DFB–Like Photonic Crystal Waveguide Lasers 100 3.2.2.2 α DFB Lasers 102 3.2.2.3 Ridge Waveguide Lasers with Photonic Crystal Mirrors 103 3.2.3 Photonic Crystal Surface–Emitting Lasers (PCSELs) 106 3.2.4 Nonradiative Carrier Recombination in Photonic Crystal Laser Diodes 109 3.3 Mid–Infrared and Terahertz (THz) Quantum Cascade Lasers 112 3.3.1 Microdisk QCLs 114 3.3.1.1 Microdisk QC Lasers at Mid–Infrared Wavelengths 114 3.3.1.2 THz Waves: Several Closely Spaced Demonstrations of Small Volume Micro–Lasers Exploiting Double–Sided Metallic Cavities 115 3.3.2 Photonic Crystal QCLs: Surface Emission and Small Modal Volumes 116 3.3.2.1 Mid–Infrared Quantum Cascade Lasers with Deeply Etched Photonic Crystal Structures 116 3.3.2.2 Mid–Infrared Quantum Cascade Lasers with Thin Metallic Photonic Crystal Layer 121 3.3.2.3 Terahertz (THz) 2D Photonic Crystal Quantum–Cascade (QC) Lasers 123 3.3.3 Toward THz QC Lasers with Truly Subwavelength Dimensions 131 3.4 Concluding Remarks and Prospects 135 References 138 4 Photonic–Crystal VCSELs 149 Krassimir Panajotov, Maciej Dems, and Tomasz Czyszanowski 4.1 Introduction 149 4.2 Numerical Methods for Modeling Photonic–Crystal VCSELs 156 4.3 Plane–Wave Admittance Method 158 4.4 Impact of Photonic–Crystal depth on VCSEL Threshold Characteristics 166 4.5 Top and Bottom–Emitting Photonic–Crystal VCSELs 170 4.6 Enhanced Fundamental Mode Operation in Photonic–Crystal VCSELs 173 4.7 Highly Birefringent and Dichroic Photonic–Crystal VCSELs 177 4.8 Photonic–Crystal VCSELs with True Photonic Bandgap 181 4.9 Summary and Prospects 185 References 188 5 III–V Compact Lasers Integrated onto Silicon (SOI) 195 Geert Morthier, Gunther Roelkens, and Dries Van Thourhout 5.1 Introduction 195 5.2 Bonding of III–V Membranes on SOI 197 5.2.1 Adhesive Bonding 199 5.2.2 Direct Bonding 201 5.2.3 Substrate Removal 203 5.3 Heterogeneously Integrated Edge–Emitting Laser Diodes 204 5.3.1 Fabry–Perot Lasers 205 5.3.2 Mode–Locked Lasers 207 5.3.3 Racetrack Resonator Lasers 207 5.3.4 DFB and Tunable Lasers 209 5.3.4.1 Distributed Feedback Lasers 209 5.3.4.2 Distributed Bragg Reflector Lasers 209 5.3.4.3 Sampled Grating DBR Lasers 209 5.3.4.4 Ring–Resonator Based Tunable Laser 210 5.3.4.5 Heterogeneously Integrated Multiwavelength Laser 210 5.3.5 Proposed Novel Laser Architectures 211 5.3.5.1 Exchange Bragg Coupling Laser Structure 211 5.3.5.2 Resonant Mirrors 211 5.3.6 Heat Sinking Strategies for Heterogeneously Integrated Lasers 212 5.4 Microdisk and Microring Lasers 213 5.4.1 Design of Microdisk Lasers 215 5.4.2 Static Operation 217 5.4.3 Dynamic Operation and Switching 219 5.4.3.1 Direct Modulation 219 5.4.3.2 All–Optical Set–Reset Flip–Flop 219 5.4.3.3 Gating and Wavelength Conversion 221 5.4.3.4 Narrowband Optical Isolation and Reflection Sensitivity of Microdisk Lasers 222 5.4.3.5 Phase Modulation 224 5.4.3.6 Microwave Photonic Filter 224 5.5 Summary and Conclusions 226 References 226 6 Semiconductor Micro–Ring Lasers 231 G´abor Mezosi and Marc Sorel 6.1 Introduction 231 6.2 Historical Review of Major Contributions to Research on SRL Devices 232 6.3 Waveguide Design of Semiconductor Ring Lasers 235 6.4 Bending Loss in Semiconductor Ring Lasers 238 6.5 Nonradiative Carrier Losses 240 6.6 Semiconductor Microring and Microdisk Lasers with Point Couplers 242 6.7 Junction Heating in Small SRL Devices 246 6.8 RIE–Lag Effects in Small SRL Devices 248 6.9 Racetrack Geometry Microring Lasers 249 6.10 Chapter Summary 252 References 253 7 Nonlinearity in Semiconductor Micro–Ring Lasers 257 Xinlun Cai, Siyuan Yu, Yujie Chen, and Yanfeng Zhang 7.1 Introduction 257 7.2 General Formalism 260 7.2.1 Fundamental Equations for Semiconductor Ring Lasers 260 7.2.2 Third Order Susceptibility and Polarization 265 7.2.3 Generalized Equations in Matrix Form 270 7.3 Numerical Results for Micro–Ring Lasers 272 7.3.1 L–I Characteristics 274 7.3.2 Temporal Dynamics and Lasing Spectra 275 7.3.3 Lasing Direction Hysteresis 277 7.3.4 Experimental Results for Racetrack Shaped SRLs 281 7.4 Numerical Results for Unidirectional Micro–Ring Lasers 283 7.4.1 Unidirectional SRL 284 7.4.2 Impact of the Feedback Strength on the Operation of Unidirectional SRL 287 7.5 Summary and Conclusions 293 References 294 Index 297

Richard De La Rue has been Professor of Optoelectronics at Glasgow University since 1986. Jean–Michel Lourtioz is Director of Research at the "Centre National de la Recherche Scientifique" (CNRS, France). Siyuan Yu is Professor of Photonic Information Systems at the Department of Electronic and Electrical Engineering, University of Bristol, England, UK. The research of Richard De La Rue has been concerned with photonic crystal and photonic wire structures, with waveguide micro–cavities and with meta–materials. This research is targeted at applications in both communications and sensing. His research in the area of photonic crystals has evolved to cover compact lasers, planar micro–cavities, photonic–crystal LEDs, photonic integrated circuits (PICs), synthetic opal and inverse opal structures. Since 1976, the research work of Jean– Michel Lourtioz with the "Institut d′Electronique Fondamentale" at Paris–Sud University has covered a broad variety of topics including: molecular lasers, semiconductor lasers, fast optoelectronics, quantum well intersubband devices, semiconductor nanostructures, photonic crystals and metamaterials. He has recently reoriented a part of his activities to the development of research projects in nanobiotechnology. Siyuan Yuis is also a Special Expert Professor at the State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat–sen University, Guangzhou, China.  His research has been mainly concerned with III–V semiconductor based integrated photonic components and their applications in optical communications systems, covering semiconductor optical amplifiers, semiconductor lasers, integrated optical switch matrices, all–optical wavelength convertors and all–optical signal processing devices.