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

The concept of multi-homodyne coherent detection is used for stealth and secured optical communications, demonstrating a transmission rate of 20 Gbps under negative (in dB) optical signal-to-noise ratio (OSNR), in a deployed multi-core fiber (MCF) network. A 10 GBd QPSK signal is assigned with a bandwidth of multi-hundreds GHz, optically encoded with spectral phase mask, and transmitted below ASE noise in the MCF channel. To enable such transmission scheme, a semiconductor based gain-switched laser (GSL) frequency comb, used as both the signal carrier and local oscillator (LO), are then mixed in intradyne coherent receiver. The ultra-short time-domain overlapping between the pulsed signal and the pulsed LO allows the authorized user to collect the information, while discriminating most of the noise. Consequently, the electrical SNR is dramatically improved compared to the optical SNR, resulting in optical processing gain. Nevertheless, ultra-short pulses mixing is rather susceptible to a chromatic dispersion (CD), which imposes a major challenge in this spread-spectrum transmission technique. In this contribution, the effect of CD in multi-homodyne coherent detection is analyzed in an analytic model and in experiments. The model suggests a modified CD transfer function, comprised of the optical sampling of a conventional CD transfer function. In addition, the SNR penalty associated with the CD effect is quantified, as well as its dependency in propagation length and overall GSL's bandwidth. To circumvent the devastating effect of the CD, multi-core fibers are proposed. Two different weakly-coupled cores of a homogeneous MCF allow the signal and the LO to co-propagate through a very similar dispersive channel. A field trial in a deployed 6.29 km MCF network has validated an encrypted and stealthy 20 Gbps coherent transmission, at −2 dB OSNR.

https://ieeexplore.ieee.org/ielx7/50/4357488/10018184.pdf

A Field Trial of Multi-Homodyne Coherent Detection Over Multi-Core Fiber for Encryption and Steganography

Dispersion-induced nonlinearities in semiconductors

We present the generalized Manakov equations describing nonlinear propagation in multimode and multicore fiber structures in the presence of random mode coupling and show how they can be extended to model multimode Raman amplification.

Nonlinear Propagation in Multimode Fibers with Random Mode Coupling

Recent progress towards efficient frequency converters based on four-wave mixing in semiconductor optical amplifiers is reviewed. The role of the preamplifier in the optimization of the converter stage is pointed out.

Frequency converters based on FWM in semiconductor optical amplifiers

A system and method for increasing transmission distance and/or transmission
data rates using tedons and an encoding scheme to reduce the number of ones in a data
signal is decribed. The method for increasing transmission distance and transmission
data rate of a fiber optical communications link using tedons comprises the steps of
encoding a data signal to be transmitted using an encoding scheme that reduces a number
of ones in said data signal, transmitting said encoded data signal over said fiber optical
communications link, receiving said encoded data signal and decoding said encoded data
signal. The system for increasing transmission distance and transmission data rate of a
fiber optical communications link using tedons comprises means for encoding a data
signal to be transmitted using an encoding scheme that reduces a number of ones in said
data signal, means for transmitting said encoded data signal over said fiber optical
communications link, means for receiving said encoded data signal and means for
decoding said encoded data signal.

Antonio Mecozzi

Papers

A Field Trial of Multi-Homodyne Coherent Detection Over Multi-Core Fiber for Encryption and Steganography

Dispersion-induced nonlinearities in semiconductors

Nonlinear Propagation in Multimode Fibers with Random Mode Coupling

Frequency converters based on FWM in semiconductor optical amplifiers

Modulation scheme for short pulses having low duty-cycle