N G van Kampen 1981 Amsterdam: North-Holland xiv + 419 pp price Dfl 180 This is a book which, at a lower price, could be expected to become an essential part of the library of every physical scientist concerned with problems involving fluctuations and stochastic processes, as well as those who just enjoy a beautifully written book. It provides an extensive graduate-level introduction which is clear, cautious, interesting and readable.

https://iopscience.iop.org/article/10.1088/0031-9112/34/4/040/pdf

Stochastic Processes in Physics and Chemistry

A topical review of numerical and experimental studies of supercontinuum generation in photonic crystal fiber is presented over the full range of experimentally reported parameters, from the femtosecond to the continuous-wave regime. Results from numerical simulations are used to discuss the temporal and spectral characteristics of the supercontinuum, and to interpret the physics of the underlying spectral broadening processes. Particular attention is given to the case of supercontinuum generation seeded by femtosecond pulses in the anomalous group velocity dispersion regime of photonic crystal fiber, where the processes of soliton fission, stimulated Raman scattering, and dispersive wave generation are reviewed in detail. The corresponding intensity and phase stability properties of the supercontinuum spectra generated under different conditions are also discussed.

Supercontinuum generation in photonic crystal fiber

We describe a method to estimate the capacity limit of fiber-optic communication systems (or ?fiber channels?) based on information theory. This paper is divided into two parts. Part 1 reviews fundamental concepts of digital communications and information theory. We treat digitization and modulation followed by information theory for channels both without and with memory. We provide explicit relationships between the commonly used signal-to-noise ratio and the optical signal-to-noise ratio. We further evaluate the performance of modulation constellations such as quadrature-amplitude modulation, combinations of amplitude-shift keying and phase-shift keying, exotic constellations, and concentric rings for an additive white Gaussian noise channel using coherent detection. Part 2 is devoted specifically to the "fiber channel.'' We review the physical phenomena present in transmission over optical fiber networks, including sources of noise, the need for optical filtering in optically-routed networks, and, most critically, the presence of fiber Kerr nonlinearity. We describe various transmission scenarios and impairment mitigation techniques, and define a fiber channel deemed to be the most relevant for communication over optically-routed networks. We proceed to evaluate a capacity limit estimate for this fiber channel using ring constellations. Several scenarios are considered, including uniform and optimized ring constellations, different fiber dispersion maps, and varying transmission distances. We further present evidences that point to the physical origin of the fiber capacity limitations and provide a comparison of recent record experiments with our capacity limit estimation.

Capacity Limits of Optical Fiber Networks

Real and Complex Analysis

Squeezed states of the electromagnetic field have been generated by nondegenerate four-wave mixing due to Na atoms in an optical cavity. The optical noise in the cavity, comprised of primarily vacuum fluctuations and a small component of spontaneous emission from the pumped Na atoms, is amplified in one quadrature of the optical field and deamplified in the other quadrature. These quadrature components are measured with a balanced homodyne detector. The total noise level in the deamplified quadrature drops below the vacuum noise level.

Observation of squeezed states generated by four-wave mixing in an optical cavity

Quantum fluids of light are an emerging tool employed in quantum many-body physics. Their amazing properties and versatility allow using them in a wide variety of fields including gravitation, quantum information and simulation. However the implications of the quantum nature of light in the nonlinear optical propagation are still missing many features. We theoretically predict classical spontaneous squeezing of a photon fluid in a nonlocal nonlinear medium. By using the so called Gamow vectors, we show that the quadratures of a coherent state get squeezed and that a maximal squeezing power exists. Our analysis holds true for temporal and spatial optical propagation in highly nonlocal regime. These results open a new scenario in quantum photon fluids and may lead to novel applications in fields like metrology and analogues of quantum gravity.

Squeezing in a nonlocal photon fluid

Unified approach to stochastic representations in reaction kinetics

A new method for obtaining the probability density function of polarization mode dispersion (PMD) conditioned on the measured PMD value at an offset optical frequency is introduced. This method is advantageous in its ability to accurately and efficiently estimate the conditional distribution far in the tails.

Efficient method for the extraction of the conditional probability distribution of polarization mode dispersion

 We study the relaxation from a metastable state using a stochastic process which is related to the generating function of the system by means of Feynman-Kac formula The results of such representation are compared with direct numerical simulations of the stochastic differential equations describing system's evolution We have found that the stochastic representation is more efficient from computational point of view then the direct simulations The problems related to its numerical implementation are discussed INTRODUCTION In this paper we are concerned with numerical simulations of the escape from a metastable state caused by the presence of an external noise Such problem appears in many areas of physics and the literature on this subject is very large (see for example [1], [2]) The process of escape can be rigorously described by a Fokker-Planck equation, which gives the probability distribution of finding the system at different points of its phase space as a function of time [1] Alternatively one may introduce a set of stochastic differential equations for the process such that the ensemble of states evolving according to these equations is characterized by the time dependent probability distribution obtained from the given by the Fokker-Planck equation In the following we shall consider a very special case in which the stochastic differential equation describing the time evolution of our system has the form:

/pdf/application-of-a-stochastic-representation-in-numerical-1wbtdizzrc.pdf

Application of a stochastic representation in numerical studies of the relaxation from a metastable state

From Distributed Acoustic Sensing (DAS) measurements over deployed Multi-Core Fiber (MCF), we discuss several signal processing options to enhance the sensing sensitivity, namely core combination and longitudinal averaging.

Antonio Mecozzi

Papers

Squeezing in a nonlocal photon fluid

Unified approach to stochastic representations in reaction kinetics

Efficient method for the extraction of the conditional probability distribution of polarization mode dispersion

Application of a stochastic representation in numerical studies of the relaxation from a metastable state

Coherent combination method applied to distributed acoustic sensing over deployed multicore fiber