Laser Physics

Although the basic principles of lasers have remained unchanged in the past 20 years, there has been a shift in the kinds of lasers generating interest. Providing a comprehensive introduction to the operating principles and applications of lasers, this second edition of the classic book on the subject reveals the latest developments and applications of lasers. Placing more emphasis on applications of lasers and on optical physics, the book's self-contained discussions will appeal to physicists, chemists, optical scientists, engineers, and advanced undergraduate students.

Table of Contents:
Preface xiii 1 Introduction to Laser Operation 1 1.1 Introduction 1 1.2 Lasers and Laser Light 3 1.3 Light in Cavities 8 1.4 Light Emission and Absorption in Quantum Theory 10 1.5 Einstein Theory of Light–Matter Interactions 11 1.6 Summary 14 2 Atoms, Molecules, and Solids 17 2.1 Introduction 17 2.2 Electron Energy Levels in Atoms 17 2.3 Molecular Vibrations 26 2.4 Molecular Rotations 31 2.5 Example: Carbon Dioxide 33 2.6 Conductors and Insulators 35 2.7 Semiconductors 39 2.8 Semiconductor Junctions 45 2.9 Light-Emitting Diodes 49 2.10 Summary 55 Appendix: Energy Bands in Solids 56 Problems 64 3 Absorption, Emission, and Dispersion of Light 67 3.1 Introduction 67 3.2 Electron Oscillator Model 69 3.3 Spontaneous Emission 74 3.4 Absorption 78 3.5 Absorption of Broadband Light 84 3.6 Thermal Radiation 85 3.7 Emission and Absorption of Narrowband Light 93 3.8 Collision Broadening 99 3.9 Doppler Broadening 105 3.10 The Voigt Profile 108 3.11 Radiative Broadening 112 3.12 Absorption and Gain Coefficients 114 3.13 Example: Sodium Vapor 118 3.14 Refractive Index 123 3.15 Anomalous Dispersion 129 3.16 Summary 132 Appendix: The Oscillator Model and Quantum Theory 132 Problems 137 4 Laser Oscillation: Gain and Threshold 141 4.1 Introduction 141 4.2 Gain and Feedback 141 4.3 Threshold 143 4.4 Photon Rate Equations 148 4.5 Population Rate Equations 150 4.6 Comparison with Chapter 1 152 4.7 Three-Level Laser Scheme 153 4.8 Four-Level Laser Scheme 156 4.9 Pumping Three- and Four-Level Lasers 157 4.10 Examples of Three- and Four-Level Lasers 159 4.11 Saturation 161 4.12 Small-Signal Gain and Saturation 164 4.13 Spatial Hole Burning 167 4.14 Spectral Hole Burning 169 4.15 Summary 172 Problems 173 5 Laser Oscillation: Power and Frequency 175 5.1 Introduction 175 5.2 Uniform-Field Approximation 175 5.3 Optimal Output Coupling 178 5.4 Effect of Spatial Hole Burning 180 5.5 Large Output Coupling 183 5.6 Measuring Gain and Optimal Output Coupling 187 5.7 Inhomogeneously Broadened Media 191 5.8 Spectral Hole Burning and the Lamb Dip 192 5.9 Frequency Pulling 194 5.10 Obtaining Single-Mode Oscillation 198 5.11 The Laser Linewidth 203 5.12 Polarization and Modulation 207 5.13 Frequency Stabilization 215 5.14 Laser at Threshold 220 Appendix: The Fabry-Pérot Etalon 223 Problems 226 6 Multimode and Pulsed Lasing 229 6.1 Introduction 229 6.2 Rate Equations for Intensities and Populations 229 6.3 Relaxation Oscillations 230 6.4 Q Switching 233 6.5 Methods of Q Switching 236 6.6 Multimode Laser Oscillation 237 6.7 Phase-Locked Oscillators 239 6.8 Mode Locking 242 6.9 Amplitude-Modulated Mode Locking 246 6.10 Frequency-Modulated Mode Locking 248 6.11 Methods of Mode Locking 251 6.12 Amplification of Short Pulses 255 6.13 Amplified Spontaneous Emission 258 6.14 Ultrashort Light Pulses 264 Appendix: Diffraction of Light by Sound 265 Problems 266 7 Laser Resonators and Gaussian Beams 269 7.1 Introduction 269 7.2 The Ray Matrix 270 7.3 Resonator Stability 274 7.4 The Paraxial Wave Equation 279 7.5 Gaussian Beams 282 7.6 The ABCD Law for Gaussian Beams 288 7.7 Gaussian Beam Modes 292 7.8 Hermite–Gaussian and Laguerre–Gaussian Beams 298 7.9 Resonators for He–Ne Lasers 306 7.10 Diffraction 309 7.11 Diffraction by an Aperture 312 7.12 Diffraction Theory of Resonators 317 7.13 Beam Quality 320 7.14 Unstable Resonators for High-Power Lasers 321 7.15 Bessel Beams 322 Problems 327 8 Propagation of Laser Radiation 331 8.1 Introduction 331 8.2 The Wave Equation for the Electric Field 332 8.3 Group Velocity 336 8.4 Group Velocity Dispersion 340 8.5 Chirping 351 8.6 Propagation Modes in Fibers 355 8.7 Single-Mode Fibers 361 8.8 Birefringence 365 8.9 Rayleigh Scattering 372 8.10 Atmospheric Turbulence 377 8.11 The Coherence Diameter 379 8.12 Beam Wander and Spread 388 8.13 Intensity Scintillations 392 8.14 Remarks 395 Problems 397 9 Coherence in Atom-Field Interactions 401 9.1 Introduction 401 9.2 Time-Dependent Schrödinger Equation 402 9.3 Two-State Atoms in Sinusoidal Fields 403 9.4 Density Matrix and Collisional Relaxation 408 9.5 Optical Bloch Equations 414 9.6 Maxwell–Bloch Equations 420 9.7 Semiclassical Laser Theory 428 9.8 Resonant Pulse Propagation 432 9.9 Self-Induced Transparency 438 9.10 Electromagnetically Induced Transparency 441 9.11 Transit-Time Broadening and the Ramsey Effect 446 9.12 Summary 451 Problems 452 10 Introduction to Nonlinear Optics 457 10.1 Model for Nonlinear Polarization 457 10.2 Nonlinear Susceptibilities 459 10.3 Self-Focusing 464 10.4 Self-Phase Modulation 469 10.5 Second-Harmonic Generation 471 10.6 Phase Matching 475 10.7 Three-Wave Mixing 480 10.8 Parametric Amplification and Oscillation 482 10.9 Two-Photon Downconversion 486 10.10 Discussion 492 Problems 494 11 Some Specific Lasers and Amplifiers 497 11.1 Introduction 497 11.2 Electron-Impact Excitation 498 11.3 Excitation Transfer 499 11.4 He–Ne Lasers 502 11.5 Rate Equation Model of Population Inversion in He–Ne Lasers 505 11.6 Radial Gain Variation in He–Ne Laser Tubes 509 11.7 CO2 Electric-Discharge Lasers 513 11.8 Gas-Dynamic Lasers 515 11.9 Chemical Lasers 516 11.10 Excimer Lasers 518 11.11 Dye Lasers 521 11.12 Optically Pumped Solid-State Lasers 525 11.13 Ultrashort, Superintense Pulses 532 11.14 Fiber Amplifiers and Lasers 537 11.15 Remarks 553 Appendix: Gain or Absorption Coefficient for Vibrational-Rotational Transitions 554 Problems 558 12 Photons 561 12.1 What is a Photon 561 12.2 Photon Polarization: All or Nothing 562 12.3 Failures of Classical Theory 563 12.4 Wave Interference and Photons 567 12.5 Photon Counting 569 12.6 The Poisson Distribution 573 12.7 Photon Detectors 575 12.8 Remarks 585 Problems 586 13 Coherence 589 13.1 Introduction 589 13.2 Brightness 589 13.3 The Coherence of Light 592 13.4 The Mutual Coherence Function 595 13.5 Complex Degree Of Coherence 598 13.6 Quasi-Monochromatic Fields and Visibility 601 13.7 Spatial Coherence of Light From Ordinary Sources 603 13.8 Spatial Coherence of Laser Radiation 608 13.9 Diffraction of Laser Radiation 610 13.10 Coherence and the Michelson Interferometer 611 13.11 Temporal Coherence 613 13.12 The Photon Degeneracy Factor 616 13.13 Orders of Coherence 619 13.14 Photon Statistics of Lasers and Thermal Sources 620 13.15 Brown–Twiss Correlations 627 Problems 634 14 Some Applications of Lasers 637 14.1 Lidar 637 14.2 Adaptive Optics for Astronomy 648 14.3 Optical Pumping and Spin-Polarized Atoms 658 14.4 Laser Cooling 671 14.5 Trapping Atoms with Lasers and Magnetic Fields 685 14.6 Bose–Einstein Condensation 690 14.7 Applications of Ultrashort Pulses 697 14.8 Lasers in Medicine 718 14.9 Remarks 728 Problems 729 15 Diode Lasers and Optical Communications 735 15.1 Introduction 735 15.2 Diode Lasers 736 15.3 Modulation of Diode Lasers 754 15.4 Noise Characteristics of Diode Lasers 760 15.5 Information and Noise 774 15.6 Optical Communications 782 Problems 790 16 Numerical Methods for Differential Equations 793 16.A Fortran Program for Ordinary Differential Equations 793 16.B Fortran Program for Plane-Wave Propagation 796 16.C Fortran Program for Paraxial Propagation 799 Index 809

About the Author :
PETER W. MILONNI is currently Laboratory Fellow and Laboratory Associate in the Complex Systems Group of the Theoretical Division, Los Alamos National Laboratory and Research Professor of Physics at the University of Rochester. Dr. Milonni is the author or coauthor of several books and has published research and review papers on both pure and applied physics. He has served for many years on a number of editorial boards, and was the recipient of the Max Born Award of the Optical Society of America in 2008. His research interests are in the areas of quantum optics and electrodynamics, especially in connection with the quantum and fluctuation properties of electromagnetic radiation and its interaction with matter. JOSEPH H. EBERLY is currently Andrew Carnegie Professor Physics and Professor of Optics at the University of Rochester. A past president of the Optical Society of America, he has contributed to the research literature on theoretical quantum optics and laser physics, with interests in multipulse propogation, high-field atomic physics, quantum entanglement, cavity QED, and relaxation dynamics. Dr. Eberly received the Smoluchowski Medal of the Physical Society of Poland in 1987 and the Charles Hard Townes Award of the Optical Society of America in 1994. He is the coauthor of two books and coeditor of several conference proceedings. He is the founding editor of Optics Express and has served on a number of editorial and advisory boards.