1．Introductory Concepts

1.1．Spontaneous and Stimulated Emission,Absorption

1.2．The Laser Idea

1.3．Pumping Schemes

1.4．Properties of Laser Beams

1.4.1．Monochromaticity

1.4.2．Coherence

1.4.3．Directionality

1.4.4．Brightness

1.4.5．Short Time Duration

1.5．Types of Lasers

1.6．Organization of the Book

Problems

2．Interaction of Radiation with Atoms and Ions

2.1．Introduction

2.2．Summary of Blackbody Radiation Theory

2.2.1．Modes of a Rectangular Cavity

2.2.2．The Rayleigh-Jeans and Planck Radiation Formula

2.2.3．Planck's Hypothesis and Field Quantization

2.3．Spontaneous Emission

2.3.1．Semiclassical Approach

2.3.2．Quantum Electrodynamics Approach

2.3.3．Allowed and Forbidden Transitions

2.4．Absorption and Stimulated Emission

2.4.1．Rates of Absorption and Stimulated Emission

2.4.2．Allowed and Forbidden Transitions

2.4.3．Transition Cross Section,Absorption and Gain Coefficient

2.4.4．Einstein Thermodynamic Treatment

2.5．Line Broadening Mechanisms

2.5.1．Homogeneous Broadening

2.5.2．Inhomogeneous Broadening

2.5.3．Concluding Remarks

2.6．Nonradiative Decay and Energy Transfer

2.6.1．Mechanisms of Nonradiative Decay

2.6.2．Combined Effects of Radiative and Nonradiative Processes

2.7．Degenerate or Strongly Coupled Levels

2.7.1．Degenerate Levels

2.7.2．Strongly Coupled Levels

2.8．Saturation

2.8.1．Saturation of Absorption:Homogeneous Line

2.8.2．Gain Saturation:Homogeneous Line

2.8.3．Inhomogeneously Broadened Line

2.9．Decay of an Optically Dense Medium

2.9.1．Radiation Trapping

2.9.2．Amplified Spontaneous Emission

2.10．Concluding Remarks

Problems

References

3．Energy Levels,Radiative and Nonradiative Transitions in Molecules and Semiconductors

3.1．Molecules

3.1.1．Energy Levels

3.1.2．Level Occupation at Thermal Equilibrium

3.1.3．Stimulated Transitions

3.1.4．Rediative and Nonradiative Decay

3.2．Bulk Semiconductors

3.2.1．Electronic States

3.2.2．Density of States

3.2.3．Level Occupation at Thermal Equilibrium

3.2.4．Stimulated Transitions

3.2.5．Absorption and Gain Coefficients

3.2.6．Spontaneous Emission and Nonradiative Decay

3.2.7．Concluding Remarks

3.3．Semiconductor Quantum Wells

3.3.1．Electronic States

3.3.2．Density of States

3.3.3．Level Occupation at Thermal Equilibrium

3.3.4．Stimulated Transitions

3.3.5．Absorption and Gain Coefficients

3.3.6．Strained Quantum Wells

3.4．Quantum Wires and Quantum Dots

3.5．Concluding Remarks

Problems

References

4．Ray and Wave Propagation Through Optical Media

4.1．Introduction

4.2．Matrix Formulation of Geometrical Optics

4.3．Wave Reflection and Transmission at a Dielectric Interface

4.4．Multilayer Dielectric Coatings

4.5．The Fabry-Perot Intefferometer

4.5.1．Properties of a Fabry-Perot Interferometer

4.5.2．The Fabry-Perot Interferometer as a Spectrometer

4.6．Diffraction Optics in the Paraxial Approximation

4.7．Gaussian Beams

4.7.1．Lowest-Order Mode

4.7.2．Free Space Propagation

4.7.3．Gaussian Beams and the ABCD Law

4.7.4．Higher-Order Modes

4.8．Conclusions

Problems

References

5．Passive Optical Resonators

5.1．Introduction

5.2．Eigenmodes and Eigenvalues

5.3．Photon Lifetime and Cavity Q

5.4．Stability Condition

5.5．Stable Resonators

5.5.1．Resonators with Infinite Aperture

5.5.1.1．Eigenmodes

5.5.1.2．Eigenvalues

5.5.1.3．Standing-and Traveling-Waves in a Two-Mirror Resonator

5.5.2．Effects of a Finite Aperture

5.5.3．Dynamically and Mechanically Stable Resonators

5.6．Unstable Resonators

5.6.1．Geometrical-Optics Description

5.6.2．Wave-Optics Description

5.6.3．Advantages and Disadvantages of Hard-Edge Unstable Resonators

5.6.4．Variable-Reflectivity Unstable Resonators

5.7．Concluding Remarks

Problems

References

6．Pumping Processes

6.1．Introduction

6.2．Optical Pumpingby an Incoherent Light Source

6.2.1．Pumping Systems

6.2.2．Absorption of Pump Light

6.2.3．Pump Efficiency and Pump Rate

6.3．Laser Pumping

6.3.1．Laser Diode Pumps

6.3.2．Pump Transfer Systems

6.3.2.1．Longitudinal Pumping

6.3.2.2．Transverse Pumping

6.3.3．Pump Rate and Pump Efficiency

6.3.4．Threshold Pump Power for Four-Level and Quasi-Three-Level Lasers

6.3.5．Comparison Between Diode-pumping and Lamp-pumping

6.4．Electrical Pumping

6.4.1．Electron Impact Excitation

6.4.1.1．Electron Impact Cross Section

6.4.2．Thermal and Drift Velocities

6.4.3．Electron Energy Distribution

6.4.4．The Ionization Balance Equation

6.4.5．Scaling Laws for Electrical Discharge Lasers

6.4.6．Pump Rate and Pump Efficiency

6.5．Conclusions

Problems

References

7．Continuous Wave Laser Behavior

7.1．Introduction

7.2．Rate Equations

7.2.1．Four-Level Laser

7.2.2．Quasi-Three-Level Laser

7.3．Threshold Conditions and Output Power:Four-Level Laser

7.3.1．Space-Independent Model

7.3.2．Space-Dependent Model

7.4．Threshold Condition and Output Power:Quasi-Three-Level Laser

7.4.1．Space-Independent Model

7.4.2．Space-Dependent Model

7.5．Optimum Output Coupling

7.6．Laser Tuning

7.7．Reasons for Multimode Oscillation

7.8．Single-Mode Selection

7.8.1．Single-Transverse-Mode Selection

7.8.2．Single-Longitudinal-Mode Selection

7.8.2.1．Fabry-Perot Etalons as Mode-Selective Elements

7.8.2.2．Single Mode Selection via Unidirectional Ring Resonators

7.9 Frequency-Pulling and Limit to Monochromaticity

7.10．Laser Frequency Fluctuations and Frequency Stabilization

7.11．Intensity Noise and Intensity Noise Reduction

7.12．Conclusions

Problems

References

8．Transient Laser Behavior

8.1．Introduction

8.2．Relaxation Oscillations

8.2.1．Linearized Analysis

8.3．Dynamical Instabilities and Pulsations in Lasers

8.4．Q-Switching

8.4.1．Dynamics of the Q-Switching Process

8.4.2．Methods of Q-Switching

8.4.2.1．Electro-Optical Q-Switching

8.4.2.2．Rotating Prisms

8.4.2.3．Acousto-Optic Q-Switches

8.4.2.4．Saturable-Absorber Q-Switch

8.4.3．Operating Regimes

8.4.4．Theory of Active Q-Switching

8.5．Gain Switching

8.6．Mode-Locking

8.6.1．Frequency-Domain Description

8.6.2．Time-Domain Picture

8.6.3．Methods of Mode-Locking

8.6.3.1．Active Mode-Locking

8.6.3.2．Passive Mode Locking

8.6.4．The Role of Cavity Dispersion in Femtosecond Mode-Locked Lasers

8.6.4.1．Phase-Velocity,Group-Velocity and Group-Delay-Dispersion

8.6.4.2．Limitation on Pulse Duration due to Group-Delay Dispersion

8.6.4.3．Dispersion Compensation

8.6.4.4．Soliton-type of Mode-Locking

8.6.5．Mode-Locking Regimes and Mode-Locking Systems

8.7．Cavity Dumping

8.8．Concluding Remarks

Problems

References

9．Solid-State,Dye,and Semiconductor Lasers

9.1．Introduction

9.2．Solid-State Lasers

9.2.1．The Ruby Laser

9.2.2．Neodymium Lasers

9.2.2.1．Nd:YAG

9.2.2.2．Nd:Glass

9.2.2.3．Other Crystalline Hosts

9.2.3．Yb:YAG

9.2.4．Er:YAG and Yb:Er:glass

9.2.5．Tm:Ho:YAG

9.2.6．Fiber Lasers

9.2.7．Alexandrite Laser

9.2.8．Titanium Sapphire Laser

9.2.9．Cr:LISAF and Cr:LICAF

9.3．Dye Lasers

9.3.1．Photophysical Properties of Organic Dyes

9.3.2．Characteristics of Dye Lasers

9.4．Semiconductor Lasers

9.4.1．Principle of Semiconductor Laser Operation

9.4.2．The Homojunction Laser

9.4.3．The Double-Heterostructure Laser

9.4.4．Quantum Well Lasers

9.4.5．Laser Devices and Performances

9.4.6．Distributed Feedback and Distributed Bragg Reflector Lasers

9.4.7．Vertical Cavity Surface Emitting Lasers

9.4.8．Applications of Semiconductor Lasers

9.5．Conclusions

Problems

References

10．Gas,Chemical,Free Electron,and X-Ray Lasers

10.1．Introduction

10.2．Gas Lasers

10.2.1．Neutral Atom Lasers

10.2.1.1．Helium-Neon Lasers

10.2.1.2．Copper Vapor Lasers

10.2.2．Ion Lasers

10.2.2.1．Argon Laser

10.2.2.2．He-Cd Laser

10.2.3．Molecular Gas Lasers

10.2.3.1．The CO2 Laser

10.2.3.2．The CO Laser

10.2.3.3．The N2 Laser

10.2.3.4．Excimer Lasers

10.3．Chemical Lasers

10.3.1．The HF Laser

10.4．The Free-Electron Laser

10.5．X-ray Lasers

10.6．Concluding Remarks

Problems

References

11．Properties of Laser Beams

11.1．Introduction

11.2．Monochromaticity

11.3．First-Order Coherence

11.3.1．Degree of Spatial and Temporal Coherence

11.3.2．Measurement of Spatial and Temporal Coherence

11.3.3．Relation Between Temporal Coherence and Monochromaticity

11.3.4．Nonstationary Beams

11.3.5．Spatial and Temporal Coherence of Single-Mode and Multimode Lasers

11.3.6．Spatial and Temporal Coherence of a Thermal Light Source

11.4．Directionality

11.4.1．Beams with Perfect Spatial Coherence

11.4.2．Beams with Partial Spatial Coherence

11.4.3．The M2 Factor and the Spot-Size Parameter of a Multimode Laser Beam

11.5．Laser Speckle

11.6．Brightness

11.7．Statistical Properties of Laser Light and Thermal Light

11.8．Comparison Between Laser Light and Thermal Light

Problems

References

12．Laser Beam Transformation:Propagation,Amplification,Frequency Conversion,Pulse Compression and Pulse Expansion

12.1．Introduction

12.2．Spatial Transformation:Propagation of a Multimode Laser Beam

12.3．Amplitude Transformation:Laser Amplification

12.3.1．Examples of Laser Amplifiers:Chirped-Pulse-Amplification

12.4．Frequency Conversion:Second-Harmonic Generation and Parametric Oscillation

12.4.1．Physical Picture

12.4.1.1．Second-Harmonic Generation

12.4.1.2．Parametric Oscillation

12.4.2．Analytical Treatment

12.4.2.1．Parametric Oscillation

12.4.2.2．Second-Harmonic Generation

12.5．Transformation in Time:Pulse Compression and Pulse Expansion

12.5.1．Pulse Compression

12.5.2．Pulse Expansion

Problems

References

Appendices

A．Semiclassical Treatment of the Interaction of Radiation with Matter

B．Lineshape Calculation for Collision Broadening

C．Simplified Treatment of Amplified Spontaneous Emission

References

D．Calculation of the Radiative Transition Rates of Molecular Transitions

E．Space Dependent Rate Equations

E.1．Four-Level Laser

E.2．Quasi-Three-Level Laser

F．Theory of Mode-Locking:Homogeneous Line

F.1．Active Mode-Locking

F.2．Passive Mode-Locking

References

G．Propagation of a Laser Pulse Through a Dispersive Medium or a Gain Medium

References

H．Higher-Order Coherence

I．Physical Constants and Useful Conversion Factors

Answers to Selected Problems

Index