Phase Retrieval and Time-frequency Methods in the Measurement of Ultrashort Laser Pulses


Book Description

Recently several techniques have become available to measure the time- (or frequency- ) dependent intensity and phase of ultrashort laser pulses. One of these, Frequency-Resolved Optical Gating (FROG), is rigorous and has achieved single-laser-shot operation. FROG combines the concepts of time-frequency analysis in the form of spectrogram generation (in order to create a two-dimensional problem), and uses a phase-retrieval-based algorithm to invert the experimental data to yield the intensity and phase of the laboratory laser pulse. In FROG it is easy to generate a spectrogram of the unknown signal, and inversion of the spectrogram to recover the signal is the main goal. Because the temporal width of a femtosecond laser pulse is much shorter than anything achievable by electronics, FROG uses the pulse to measure itself. In FROG, the laser pulse is split into two replicas of itself by a partially reflecting beamsplitter, and the two replicas interact with each other in a medium with an instantaneous nonlinear-optical response. This interaction generates a signal field that is then frequency-resolved using a spectrometer. The spectrum of the signal field is measured for all relevant values of the temporal delay between the two pulses. Here, the authors employ FROG and FROG related techniques to measure the time-dependent intensity and phase of an ultrashort laser pulse.




Frequency-Resolved Optical Gating: The Measurement of Ultrashort Laser Pulses


Book Description

The Frequency-Resolved Optical-Gating (FROG) technique has revolutionized our ability to measure and understand ultrashort laser pulses. This book contains everything you need to know to measure even the shortest, weakest, or most complex ultrashort laser pulses. Whether you're an undergrad or an advanced researcher, you'll find easy-to-understand descriptions of all the key ideas behind all the FROG techniques, all the practical details of pulse measurement, and many new directions of research. This book is not like any other scientific book. It is a lively discussion of the basic concepts. It is an advanced treatment of research-level issues.




Fundamental Limitations in the Measurement and Stabilization of the Carrier-Envelope Phase of Ultrashort Laser Pulses


Book Description

The stabilization of the carrier-envelope phase of ultrashort laser pulses went through a rapid development from the first publication of a feasible concept in 1999 to being a mature tool for frequency metrology and attosecond science now. Using this technique, stabilization of the timing between the carrier wave and the envelope of a laser pulse with residual jitters of only 100 attoseconds has become possible. Naturally, the questions arises whether and how this can be further improved. The current work is devoted to determining the physical mechanisms which generate jitter in carrier-envelope phase stabilization. Furthermore, it is investigated whether there is a fundamental limitation to the achievable accuracy. To this end, two methods for removal of technical noise contributions are initially discussed. Different interferometer topologies are investigated and spurious interferometer noise is reduced by more than 40% using a commonpath layout. A novel two-detector based carrier-envelope phase retrieval technique for amplified laser pulses is demonstrated enabling the circumvention of the shot-noise constraint of the conventional extraction method to the maximum extent possible. Next, a novel feed-forward stabilization concept is developed that enables carrier-envelope phase stabilizations with only 20 attosecond residual timing jitter between carrier and envelope of the laser pulse. This feed-forward method is unconditionally stable against drop-out and permits the generation of a train of pulses with identical electric field structure with no additional measures. As the feed-forward concept widely avoids the technical noise sources of the conventional feedback stabilization, the resulting noise spectra exhibit only two unavoidable residual noise mechanisms: a highfrequency white noise floor stemming from shot noise in the carrier-envelope phase detection and a drift-like contribution with 1/f noise characteristics. Finally, the drift-like residual noise mechan




Ultrashort Laser Pulse Phenomena


Book Description

Ultrashort Laser Pulse Phenomena, Second Edition serves as an introduction to the phenomena of ultra short laser pulses and describes how this technology can be used to examine problems in areas such as electromagnetism, optics, and quantum mechanics. Ultrashort Laser Pulse Phenomena combines theoretical backgrounds and experimental techniques and will serve as a manual on designing and constructing femtosecond ("faster than electronics") systems or experiments from scratch. Beyond the simple optical system, the various sources of ultrashort pulses are presented, again with emphasis on the basic concepts and how they apply to the design of particular sources (dye lasers, solid state lasers, semiconductor lasers, fiber lasers, and sources based on frequency conversion). Provides an easy to follow guide through "faster than electronics" probing and detection methods THE manual on designing and constructing femtosecond systems and experiments Discusses essential technology for applications in micro-machining, femtochemistry, and medical imaging




Femtosecond Laser Pulses


Book Description

This smooth introduction for advanced undergraduates starts with the fundamentals of lasers and pulsed optics. Thus prepared, the student is introduced to short and ultrashort laser pulses, and learns how to generate, manipulate, and measure them. Spectroscopic implications are also discussed. The second edition has been completely revised and includes two new chapters on some of the most promising and fast-developing applications in ultrafast phenomena: coherent control and attosecond pulses.







Phase Retrieval Using Power Measurements


Book Description

"Optical signals have two basic components that are power and phase, which can be demonstrated in both time and frequency domains. The common diagnostics which are available in the market only measure power component in time or frequency domain. However in certain areas phase measurements are also required. The phase retrieval techniques are used to calculate phase measurements from different methods. There are a number of applications where phase measurements are required like astronomy, wavefront sensing technique (James Webb space telescope), x-ray crystallography, fiber optic telecommunications etc. Various phase retrieval algorithms have been used in retrieving phase measurements in temporal and frequency domains. Gerchberg Saxton Algorithm technique is an iterative phase retrieval technique which has been used in phase retrieval methods. This iterative process involves iterative Fourier transformation back and forth between the object and Fourier domains with applications of the measured data or known constraints in each domain. We worked on developing an iterative phase retrieval technique keeping Gerchberg Saxton Algorithm as the basis of it and were able to successfully demonstrate phase retrieval in both temporal and spectral forms for a) Gaussian pulses having a wide range of initial educated guess phase; b) Chirped Gaussian pulses having various amounts of chirp; c) Chirped Super Gaussian pulses having various amounts of chirp. A metrics system was denied on which phase retrieval technique's success was based showing minimization of power, phase and instantaneous frequency metrics. During the study we found that chirped super Gaussian pulses of order 4 converge better than the chirped Gaussian pulses and also explored a way to choose a good educational phase without knowledge of the actual phase. Thus, this research provided a new foundation for further research on phase retrieval techniques of Gaussian and chirped Gaussian pulses."--Abstract.







Compressed Sensing and its Applications


Book Description

This contributed volume contains articles written by the plenary and invited speakers from the second international MATHEON Workshop 2015 that focus on applications of compressed sensing. Article authors address their techniques for solving the problems of compressed sensing, as well as connections to related areas like detecting community-like structures in graphs, curbatures on Grassmanians, and randomized tensor train singular value decompositions. Some of the novel applications covered include dimensionality reduction, information theory, random matrices, sparse approximation, and sparse recovery. This book is aimed at both graduate students and researchers in the areas of applied mathematics, computer science, and engineering, as well as other applied scientists exploring the potential applications for the novel methodology of compressed sensing. An introduction to the subject of compressed sensing is also provided for researchers interested in the field who are not as familiar with it.




Introduction to Laser Spectroscopy


Book Description

Introduction to Laser Spectroscopy is a well-written, easy-to-read guide to understanding the fundamentals of lasers, experimental methods of modern laser spectroscopy and applications. It provides a solid grounding in the fundamentals of many aspects of laser physics, nonlinear optics, and molecular spectroscopy. In addition, by comprehensively combining theory and experimental techniques it explicates a variety of issues that are essential to understanding broad areas of physical, chemical and biological science. Topics include key laser types - gas, solid state, and semiconductor - as well as the rapidly evolving field of ultrashort laser phenomena for femtochemistry applications. The examples used are well researched and clearly presented. Introduction to Laser Spectroscopy is strongly recommended to newcomers as well as researchers in physics, engineering, chemistry and biology. * A comprehensive course that combines theory and practice * Includes a systematic and comprehensive description for key laser types * Written for students and professionals looking to gain a thorough understanding of modern laser spectroscopy