No description available.

No description available.

by So-kuen C. Liew. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves [40-45, 3rd gp.]) and index. / Abstract --- p.ii / Acknowledgments --- p.iv / Table of Contents --- p.v / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Distributed Feedback Lasers --- p.1 / Chapter 1.2 --- Computer Model --- p.6 / Chapter 1.3 --- Analyses --- p.8 / Chapter 1.4 --- Organization of Thesis --- p.11 / Chapter 2 --- Computer Model --- p.13 / Chapter 2.1 --- Comparison of Theoretical Models --- p.15 / Chapter 2.2 --- Assumptions and Approximations --- p.17 / Chapter 2.2.1 --- Longitudinal Spatial Hole Burning --- p.17 / Chapter 2.2.2 --- Spontaneous Emission --- p.18 / Chapter 2.2.3 --- Nonlinear Gain Saturation --- p.19 / Chapter 2.2.4 --- Carrier-Induced Index Change --- p.20 / Chapter 2.2.5 --- Single-mode Operation Assumption --- p.22 / Chapter 2.2.6 --- Otbers --- p.22 / Chapter 2.3 --- Theories and Approaches --- p.25 / Chapter 2.3.1 --- Coupled Wave Theory --- p.25 / Description --- p.25 / Stop-Band --- p.29 / Second-Order DFB Laser --- p.30 / DFB Designs To Improve SMSR --- p.30 / Chapter 2.3.2 --- Transfer Matrix Approach --- p.32 / Chapter 2.4 --- Above-Threshold Model --- p.34 / Chapter 2.4.1 --- Introduction --- p.34 / Chapter 2.4.2 --- Formalism --- p.36 / Facet Output Power and Optical Spectrum --- p.39 / Photon Density Distribution --- p.41 / Variance of Photon Density Distribution --- p.42 / Nearfield Distribution --- p.42 / Surface Emission --- p.43 / Power-Current Characteristics --- p.44 / Optical spectrum --- p.45 / Subthreshold Analysis --- p.47 / Linear Yield Analysis --- p.47 / Chapter 2.4.3 --- Computer Implementation --- p.48 / Flowchart --- p.48 / Subroutines --- p.52 / "Runtime, Numerical Stability" --- p.56 / Chapter 2.5 --- "Discussion,Summary and Future Work" --- p.59 / Chapter 2.5.1 --- Validation of the DFB Model --- p.59 / Chapter 2.5.2 --- Summary --- p.67 / Chapter 2.5.3 --- Topics for Future Work in Theoretical Modeling --- p.68 / Chapter 3 --- Analysis of DFBDBR Laser --- p.72 / Chapter 3.1 --- Introduction --- p.72 / Chapter 3.2 --- Subthreshold Analysis --- p.78 / Chapter 3.2.1 --- Introduction --- p.78 / Chapter 3.2.2 --- Results --- p.81 / Symmetric End-Sections --- p.81 / Asymmetric End-Sections --- p.85 / Chapter 3.3 --- Above-threshold Analysis --- p.88 / Chapter 3.3.1 --- Analysis --- p.89 / Chapter 3.3.2 --- Length Ratio --- p.92 / Chapter 3.3.3 --- Design Plot --- p.99 / Chapter 3.3.4 --- Longitudinal Spatial Hole Burning --- p.102 / Chapter 3.3.5 --- Effective Linewidth Enhancement Factor --- p.104 / Chapter 3.3.6 --- Asymmetric DFBDBR --- p.107 / Chapter 3.4 --- Conclusion --- p.109 / Chapter 4 --- Analysis of Complex-Coupled DFB --- p.110 / Chapter 4.1 --- Introduction --- p.110 / Chapter 4.2 --- Laser Structure --- p.113 / Chapter 4.2.1 --- Grating Layer --- p.114 / Chapter 4.2.2 --- Parameter Values --- p.119 / Chapter 4.3 --- Above-Threshold Analysis of CCDFB --- p.122 / Chapter 4.3.1 --- Threshold Current --- p.122 / Grating Duty Cycle = 0.36 --- p.122 / Grating Duty Cycle = 0.15 --- p.128 / Chapter 4.3.2 --- Power Efficiency --- p.131 / Grating Duty Cycle = 0.36 --- p.131 / Grating Duty Cycle = 0.15 --- p.136 / Chapter 4.3.3 --- Summary --- p.137 / Chapter 4.4 --- Yield Analysis of LCDFB and QWDFB --- p.138 / Chapter 4.4.1 --- Introduction --- p.138 / Chapter 4.4.2 --- Method --- p.140 / Chapter 4.4.3 --- Results --- p.141 / Facet Phase Angle --- p.141 / Quarterwave Phase-Shifted DFB Laser --- p.144 / Loss-Coupled DFB Laser --- p.148 / Chapter 4.5 --- Conclusion --- p.154 / Chapter 5 --- Summary and Conclusion --- p.157 / Chapter 5.1 --- Summary --- p.157 / Chapter 5.1.1 --- Summary of Major Contributions --- p.157 / Chapter 5.1.2 --- Summary of Modeling and Validation --- p.159 / Chapter 5.1.3 --- Summary of Model Applications --- p.160 / DFBDBR Laser --- p.161 / Loss-Coupled DFB Laser --- p.162 / Chapter 5.2 --- Topics for Future Studies --- p.163 / References --- p.R-l / Appendices --- p.A-l / Chapter A. --- Derivations --- p.A-l / Chapter A.1 --- Noise Power --- p.A-l / Chapter A.2 --- Product of Field Vector and Its Adjoint --- p.A-2 / Chapter A.3 --- Gain-Coupling Coefficient --- p.A-5 / Chapter B. --- Subroutines in Computer Program --- p.A-8 / Chapter B.l --- Subroutines in 'drive.f' --- p.A-8 / Chapter B.2 --- Subroutines in 'Core.f' --- p.A-9 / Chapter B.3 --- Subroutines in 'initiaLf' --- p.A-13 / Chapter B.4 --- Subroutines in ´بmisc.f' --- p.A-14 / Chapter C. --- List of Figures --- p.A-17 / Chapter D. --- List of Tables --- p.A-22 / Chapter E. --- List of Abbreviations and Acronyms --- p.A-23 / Chapter F. --- List of Symbols --- p.A-24 / Chapter G. --- List of Publications --- p.A-27 / Index --- p.I-1

by Ho Hing Wa. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references. / Abstracts in English and Chinese. / Abstract --- p.i / 摘要 --- p.iii / Acknowledgment --- p.iv / Table of Contents --- p.v / Chapter 1 --- Introduction / Chapter 1.1 --- Background of optical generation of millimeter-waves --- p.1 -1 / Chapter 1.2 --- Application of the two-section DFB laser on optical generation of millimeter-waves --- p.1 -4 / Chapter 1.3 --- Analysis --- p.1-4 / Chapter 1.4 --- Organization of Thesis --- p.1 -5 / References --- p.1-6 / Chapter 2 --- Techniques of Optical Generation of Millimeter-waves / Chapter 2.1 --- Direct modulation and mode-locking of lasers --- p.2-1 / Chapter 2.2 --- Beating of two optical waves --- p.2-3 / References --- p.2-11 / Chapter 3 --- Experimental Results and Discussions / Chapter 3.1 --- Device structure and experimental setup --- p.3-1 / Chapter 3.2 --- Light-Current Characteristics of the two-section laser --- p.3-3 / Chapter 3.3 --- Spectral behaviours of the two-section DFB laser --- p.3-5 / Chapter 3.3.1 --- Linewidth of the two-section DFB laser --- p.3-5 / Chapter 3.3.2 --- Wavelength tuning of the two-section DFB laser --- p.3-5 / Chapter 3.3.3 --- Biasing conditions for the dual-mode oscillations --- p.3-16 / Chapter 3.4 --- Optical generation of millimeter-waves --- p.3-17 / Chapter 3.4.1 --- Mechanism of beating --- p.3-17 / Chapter 3.4.2 --- Generation of millimeter-waves by optical beating --- p.3-20 / Chapter 3.5 --- Optical Transmission of the millimeter-waves --- p.3-22 / References --- p.3-24 / Chapter 4 --- Theory of DFB Laser / Chapter 4.1 --- Development of DFB laser --- p.4-1 / Chapter 4.2 --- Structure of DFB laser --- p.4-2 / Chapter 4.3 --- Model of one-section DFB laser --- p.4-4 / Chapter 4.4 --- Analysis of two-section DFB laser --- p.4-10 / Chapter 4.4.1 --- Introduction of transfer matrix method --- p.4-11 / Chapter 4.4.2 --- Formulation of transfer matrix --- p.4-12 / Chapter 4.4.3 --- Application of the transfer matrix --- p.4-13 / References --- p.4-17 / Chapter 5 --- Numerical Analysis of the Spectral Behaviours of the Two-Section DFB Laser / Chapter 5.1 --- Solving the Transcendental Equation --- p.5-1 / Chapter 5.2 --- Simulation of the spectral behaviour of the two-section DFB laser --- p.5-4 / Chapter 5.2.1 --- Assumptions and Approximations --- p.5-4 / Chapter 5.2.2 --- Parameters --- p.5-5 / Chapter 5.2.3 --- Computer Implementation --- p.5-6 / Chapter 5.2.4 --- Results and Discussion --- p.5-7 / References --- p.5-14 / Chapter 6 --- Conclusion / Chapter 6.1 --- Summary --- p.6-1 / Chapter 6.2 --- Future works --- p.6-2 / Appendices / Appendix A Source code for simulation of spectral behaviours of the two-section DFB laser --- p.A-1

Fok Mei-po. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 81-82). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.iv / Table of Content --- p.v / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Overview of Injection Locking --- p.2 / Chapter 1.2 --- Applications of Single Wavelength Injection Locking --- p.4 / Chapter 1.3 --- Applications of Multi-wavelength Injection Locking --- p.5 / Chapter 1.4 --- Organization of Thesis --- p.6 / Chapter 2 --- Principle and Theory --- p.10 / Chapter 2.1 --- Principle of Injection Locking --- p.11 / Chapter 2.2 --- Amplitude Equalization by Injection Locking --- p.14 / Chapter 2.3 --- Repolarization by Injection Locking --- p.16 / Chapter 2.4 --- Reduction of Relative Intensity Noise --- p.18 / Chapter 2.5 --- Multi-wavelength Injection Locking --- p.20 / Chapter 2.6 --- Polarization Maintaining Fiber Loop Mirror Filter --- p.21 / Chapter 2.7 --- Self-phase Modulation --- p.23 / Chapter 3 --- Preliminary Experimental Study --- p.26 / Chapter 3.1 --- Reduction of Amplitude Modulation --- p.27 / Chapter 3.2 --- Repolarization --- p.33 / Chapter 3.3 --- Relative Intensity Noise and Relaxation Oscillation Frequency --- p.35 / Chapter 3.4 --- Spurious Free Dynamic Range --- p.38 / Chapter 4 --- Optical mm-wave Generation --- p.42 / Chapter 4.1 --- Introduction --- p.43 / Chapter 4.2 --- Experimental Details --- p.44 / Chapter 4.3 --- Results and Discussion --- p.46 / Chapter 4.4 --- Summary --- p.52 / Chapter 5 --- Two-mode Injection Locking for Wavelength-tunable Pulse Generation --- p.56 / Chapter 5.1 --- Introduction --- p.57 / Chapter 5.2 --- Experimental Details --- p.58 / Chapter 5.3 --- Results and Discussion --- p.60 / Chapter 5.4 --- Summary --- p.64 / Chapter 6 --- Multi-wavelength Injection Locking Using a Polarization Maintaining Fiber Loop Mirror Filter --- p.67 / Chapter 6.1 --- Introduction --- p.69 / Chapter 6.2 --- Preliminary Study of the Generation of Multi-wavelength Injection Source --- p.70 / Chapter 6.3 --- Experimental Details --- p.73 / Chapter 6.4 --- Results and Discussion --- p.75 / Chapter 6.5 --- Summary --- p.80 / Chapter 7 --- Conclusion and Future Work --- p.83 / Chapter 7.1 --- Conclusion --- p.84 / Chapter 7.2 --- Future Work --- p.87 / Appendices --- p.A-i / Appendix A. List of Publication --- p.A-i / Appendix B. List of Figures --- p.A-iii

Not available / text

This thesis presents an investigation of the modal gain characteristics of Vertical Cavity Surface Emitting Lasers (VCSELs). This is motivated by the experimental observations which tend to indicate fundamental mode operation at just above lasing threshold and multi-transverse mode operation at higher injection current levels. The complete mode spectrum of the cylindrical cavity is first analysed to illustrate that the original expectations that single (wavelength) mode operation solely due to the large wavelength separation created by short device lengths may not be realisable. The modal gains of different modes are calculated to demonstrate that mainly the difference between the modal gains, and not the separation between the resonances, provides a more satisfactory explanation of the fundamental mode operation at just above lasing threshold. At higher injection current levels, the increase in the modal gains of the higher order transverse modes (due to spatial hole burning) explains the excitation of higher order transverse lasing modes. The model relies on calculating the modes of a cylindrical dielectric resonator and the the corresponding modal gains are obtained from a perturbation analysis which takes into account the gain profile due to the injected inversion population distribution. A self consistent evaluation of the inversion population distribution (which provides the required local gain profile) is derived from the corresponding diffusion equation for the injected carriers in the active layer of the device. The development for obtaining the above lasing threshold inversion population distribution (which includes radial and azimuthal variation) has been done hierarchically such that the numerical procedures developed in the simpler stages of the model directly apply to solve a part of the next level of sophistication. This hierarchy has helped to provide a very efficient and compact numerical procedure and may be seen as an important aspect of the work done in the thesis. Further refinements include the evaluation of the injection current profile dependence on injection contact geometry and current spreading.

Strained layers are incorporated into many electronic devices and particularly into semiconductor lasers. These strained layers can relax, both elastically and plastically, which often impairs the performance of the device. This thesis presents several methods for calculating elastic strain relaxation: a Fourierseries method for stresses imposed on the surfaces of a rectangular block; a Fourier-integral for stress imposed on the surfaces of an infinite layer; and a Green-function method for the stress field about buried inclusions. The methods are used to calculate the strain distributions in a transmission electron microscopy sample, the relaxation at the end facet of a strained-layer laser, and the strain field about a rectangular buried layer. The effects of the strain relaxation on the optical absorption of the laser facet and the zone-centre band structure of the buried layer are discussed. The equilibrium theory of critical thickness is examined in detail and is shown to make unreasonable predictions for highly strained layers; a modification which corrects this behaviour is suggested. The equilibrium theory equates the line tension of a strain relieving dislocation to the strain energy it relieves in the layer. The additional energy corrections which can be included in the line tension are discussed, together with the failure of the equilibrium theories to reliably predict plastic relaxation in all situations.

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

No description available.