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Glossary of Symbols

Introduction to Optical Pulses

Introduction

Optical Pulses in the Time Domain

Optical Pulses in the Frequency Domain

Bandwidth-Limited Pulses

Pulse Trains and Frequency Combs

Carrier-Envelope Offset

Overview on Laser Sources for Optical Pulses

Q Switching

The Principle of Q switching

Active and Passive Q Switching

Essentials of Laser Dynamics

Pumping the Gain Medium

Dynamics of Active Q Switching

Achievable Pulse Energy

Pulse Duration and Build-Up Time

Influence of the Pulse Repetition Rate

Dynamics of Passive Q Switching

Pulse duration and Pulse Energy

Saturable Absorbers for Q Switching

Influence of Pump Fluctuations

Mode Beating in Multimode Lasers

Q-Switched Solid-State Bulk Lasers

Q-Switched Microchip Lasers

Q-Switched Fiber Lasers

Multiple Pulsing and Instabilities

Cavity Dumping

Gain Switching

Gain Switching

Comparison with Other Techniques

Mode Locking

Active Mode Locking

Passive Mode Locking

Mode Locking with Fast Saturable Absorbers

Mode Locking with Slow Saturable Absorbers

Chromatic Dispersion

Dispersive Pulse Broadening

Effect of Dispersion in Mode-Locked Lasers

Dispersion Compensation in Laser Resonators

The Kerr Nonlinearity

Self-Phase Modulation

Optical Solitons

Quasi-Soliton Pulses in Laser Resonators

Semiconductor Saturable Absorbers

Other Saturable Absorbers for Mode Locking

Initiation of Mode Locking

Q-Switching Instabilities

Actively Mode-Locked Solid-State Bulk Lasers

Harmonic Mode Locking

Passively Mode-Locked Solid-State Bulk Lasers

Performance Figures of Mode-Locked Bulk Lasers

Choice of Solid-State Gain Media

Additive-Pulse Mode Locking

Kerr Lens Mode Locking

Generation of Few-Cycle Pulses

Mode-Locked High-Power Thin-Disk Lasers

Miniature Lasers with High Repetition Rates

Mode-Locked Fiber Lasers

Soliton Fiber Lasers

Limitations of Soliton Fiber Lasers

Stretched-Pulse Fiber Lasers

Similariton Fiber Lasers

Mode-Locked Diode Lasers

Mode-Locked VECSELs

Frequency Combs and Carrier-Envelope Offset

Instabilities of Mode-Locked Lasers

Cavity Dumping

Amplification of Ultrashort Pulses

Essential Issues: Dispersion and Nonlinearities

Multipass Solid-State Bulk Amplifiers

Regenerative Amplifiers

Fiber Amplifiers

Chirped-Pulse Amplification

Optical Parametric Amplifiers

Pulse Characterization

Overview on Pulse Characterization

Autocorrelators

Measurement of Pulse Energy and Peak Power

Pulse Characterization with FROG

Pulse Characterization with SPIDER

Measurement of the Carrier-Envelope Offset

Timing Jitter of Mode-Locked Lasers

Measurement of Timing Jitter

Bibliography

Index

Introduction

An optical pulse is a flash of light. Lasers and related devices have an amazing potential for generating light pulses with very special properties:

• There is a wide range of techniques for generating pulses with durations of nanoseconds, picoseconds, or even femtoseconds with lasers. Such short durations make light pulses very interesting for many applications, such as telecommunications or ultraprecise measurements of various kinds.
  


• Laser pulses are essentially always delivered in the form of a laser beam (i.e., they propagate in a well-defined direction). The high spatial coherence of such beams allows laser pulses to focus to very small spots, sometimes with areas below 1 μm². The combination of a small spot size with a short pulse duration leads to very high optical intensities, even if the pulse energy is moderate. The deposition of energy with extremely high concentration in both space and time is essential for applications in material processing, such as micromachining, where it is exploited that ultrashort pulses create only a very small heat-affected zone around a cut. Other applications are in fundamental sciences (e.g., for the study of matter under the influence of extremely high optical intensities).
  


• In some cases, the high temporal coherence within trains of ultrashort pulses is essential. For example, ultraprecise optical clocks exploit this feature.

It is important to note that laser pulses span an enormously large parameter space in terms of pulse duration, pulse energy, and wavelength. This is possible only with a wide range of techniques, the most common of which are discussed in this Field Guide.