There has recently been a renewed effort to develop coherent optical communication systems. In particular, differential phase-shift keying (DPSK), which does not require a local oscillator to perform decoding, is the focus of the attention and is perceived to be the promising candidate for future optical communication systems updates. This motivates us to exploit DPSK in wavelength-division multiplexed systems. First, modulation formats based on phase show an increased robustness to nonlinear impairments such as cross-phase modulation (XPM) and nonlinear polarization rotation, primarily because the time dependence of the optical power is deterministic and periodic. Second, coherent formats allow a higher spectral efficiency since both in-phase and quadrature dimensions of the signal space are available to encode information. Optical phase is also used in intensity-modulated direct detection systems as an extra degree of freedom, for example to provide better resistance to intrachannel four-wave mixing (FWM) or to increase spectral efficiency in duobinary modulation. Finally, phase modulation outperforms its intensity counterpart in terms of sensitivity since a 3 dB improvement can be achieved when balanced detection is used. Nevertheless, DPSK-based formats show a different behavior to noise accumulated along the propagation. Noise-induced power fluctuations are converted into phase fluctuations by the Kerr effect and become a penalty source that limits the transmission system reach. In this context, there have been intense research activities for evaluating phase uncertainties, but the previous studies assume an analytically determined pulse shape and a constant-dispersion optical link that is far from reflecting the actual and future structures of transmission lines. The objective of the proposed research is to investigate new and more efficient techniques in numerical evaluation and experimental measurement of phase jitter impact on more general communication systems, including dispersion management, filtering, and spectral inversion schemes.

This book covers the essentials of phase-stepping algorithms used in interferometry and pseudointerferometric techniques. It presents the basic concepts and mathematics needed for understanding modern phase estimation methods. The book first focuses on phase retrieval from image transforms using a single frame. It then examines the local environment of a fringe pattern, the phase estimation approach based on local polynomial phase modeling, temporal high-resolution phase evaluation methods, and methods of phase unwrapping. It also discusses experimental imperfections liable to adversely influence the accuracy of phase measurements.

Gain an intuitive understanding of jitter and phase noise with this authoritative guide. Leading researchers provide expert insights on a wide range of topics, from general theory and the effects of jitter on circuits and systems, to key statistical properties and numerical techniques. Using the tools provided in this book, you will learn how and when jitter and phase noise occur, their relationship with one another, how they can degrade circuit performance, and how to mitigate their effects - all in the context of the most recent research in the field. Examine the impact of jitter in key application areas, including digital circuits and systems, data converters, wirelines, and wireless systems, and learn how to simulate it using the accompanying Matlab code. Supported by additional examples and exercises online, this is a one-stop guide for graduate students and practicing engineers interested in improving the performance of modern electronic circuits and systems.

Over the last few years, there has been a convergence between the fields of ultrafast science, nonlinear optics, optical frequency metrology, and precision laser spectroscopy. These fields have been developing largely independently since the birth of the laser, reaching remarkable levels of performance. On the ultrafast frontier, pulses of only a few cycles long have been produced, while in optical spectroscopy, the precision and resolution have reached one part in Although these two achievements appear to be completely disconnected, advances in nonlinear optics provided the essential link between them. The resulting convergence has enabled unprecedented advances in the control of the electric field of the pulses produced by femtosecond mode-locked lasers. The corresponding spectrum consists of a comb of sharp spectral lines with well-defined frequencies. These new techniques and capabilities are generally known as “femtosecond comb technology. ” They have had dramatic impact on the diverse fields of precision measurement and extreme nonlinear optical physics. The historical background for these developments is provided in the Foreword by two of the pioneers of laser spectroscopy, John Hall and Theodor Hänsch. Indeed the developments described in this book were foreshadowed by Hänsch’s early work in the 1970s when he used picosecond pulses to demonstrate the connection between the time and frequency domains in laser spectroscopy. This work complemented the advances in precision laser stabilization developed by Hall.