Monte Carlo simulations of pulse propagation in massive multichannel optical fiber communication systems

We study the combined effect of delayed Raman response and bit pattern randomness on pulse propagation in massive multichannel optical fiber communication systems. The propagation is described by a perturbed stochastic nonlinear Schr\"odinger equation, which takes into account changes in pulse amplitude and frequency as well as emission of continuous radiation. We perform extensive numerical simulations with the model, and analyze the dynamics of the frequency moments, the bit-error-rate, and the mutual distribution of amplitude and position. The results of our numerical simulations are in good agreement with theoretical predictions based on the adiabatic perturbation approach.Comment: Submitted to Physical Review E. 8 pages, 5 figure

16x125 Gb/s Quasi-Nyquist DAC-Generated PM-16QAM Transmission Over 3590 km of PSCF

We report on a transmission experiment over high-performance pure silica core fiber (PSCF) of 16 Nyquist wavelength-division-multiplexed (Nyquist-WDM) channels at a symbol rate of 15.625 GBaud, using polarization-multiplexed (PM) 16 symbols quadrature amplitude modulation (16QAM), resulting in a per-channel raw bit rate of 125 Gb/s. The channel spacing is 16 GHz, corresponding to 1.024 times the symbol rate. The interchannel crosstalk penalty is drastically reduced through the confinement of the signal spectrum within a near-Nyquist bandwidth, achieved with digital filtering and digital-to-analog converters (DACs) operating at 1.5 samples/symbol. The optical line is a recirculating loop composed of two spans of high-performance PSCF with erbium-doped fiber amplifiers only. The transmission distance of 3590 km at a target line bit-error rate (BER) of 1.5 10^-2 is achieved at a raw spectral efficiency (SE) of 7.81 b/s/Hz. Assuming a commercial hard forward error correction with 20.5% redundancy, capable of handling the target BER, the net SE is 6.48 b/s/Hz, the highest so far reported for multithousand kilometer transmission of PM-16QAM at ≥ 100 Gb/s per channel. These results demonstrate the feasibility of very high SE DAC-enabled ultra-long-haul quasi-Nyquist-WDM transmission using PM-16QAM with current technologies and manageable digital signal processing complexit

Real-time monitoring of the impact of cascaded wavelength-selective switches in digital coherent receivers

A simple real-time monitoring algorithm for the impact of cascaded WSSs in elastic optical networks, which exploits the information available in a digital coherent receiver, is proposed and demonstrated through both numerical simulations and experiments

Two-Fiber Self-Homodyne Transmission for Short-Reach Coherent Optical Communications

We experimentally evaluate the performance of two-fiber self-homodyne short-reach transmission, showing that it enables the use of DFB laser provided that the optical path mismatch is kept below 1 m for PM-QPSK and 0.5 m for PM-16QAM

Direito Empresarial Contemporâneo: O Caso Banksy

The interaction between business law and art galleries is hit by the work of the English artist Banksy. This article addresses new prospects for urban artists and business law in contemporary times. This paper presents, under an interdisciplinary perspective, some areas of application of business law, especially the protection, or not, of intellectual property, in the case of urban works of art. The article presents the case Banksy and his work in the urban environment, sometimes in public property, sometimes in private buildings, and, from a historical review of the protection of intellectual property, especially in the case of protection of a work of arts, this text examines the challenges that the unusual creation of Banksy presents to contemporary business law.O Direito empresarial e as grandes galerias de arte são provocados pela obra do artista inglês Banksy; este ensaio discute as novas perspectivas para os artistas urbanos e para o Direito empresarial na contemporaneidade. Este texto apresenta, sob uma perspectiva interdisciplinar, algumas áreas de aplicação do direito de empresa, especialmente quanto à proteção, ou não, da propriedade intelectual, no caso da arte urbana. O artigo apresenta o caso Banksy e suas obras em ambientes urbanos, ora públicos, ora privados, e, a partir de uma revisão histórica sobre a proteção da propriedade intelectual, ainda que se trate da proteção de uma obra de arte, analisa os desafios que a inusitada criação do autor Banksy coloca para o direito de empresa

A Simple and Effective Closed-Form GN-Model Correction Formula Accounting for Signal Non-Gaussian Distribution

The GN model of non-linear fiber propagation has been shown to overestimate the variance of non-linearity due to the signal Gaussianity approximation, leading to maximum reach predictions for realistic optical systems which may be pessimistic by about 5% to 15%, depending on fiber type and system set-up. Analytical corrections have been proposed, which however substantially increase the model complexity. In this paper we provide a simple closed-form GN model correction formula, derived from the EGN model, which we show to be quite effective in correcting for the GN model tendency to overestimate non-linearity. The formula also permits to clearly identify the correction dependence on key system parameters, such as span length and loss.Comment: This paper has been accepted for publication in the IEEE Journal of Lightwave Technolog

Phase Noise Impact and scalability of self-homodyne short-reach coherent transmission using DFB lasers

We investigate on a two-fiber short-reach self-homodyne coherent transmission system without optical amplification, where the same transmission laser is used to generate a modulated signal carrying useful data and a continuous wave signal, which serves as a local oscillator at the receiver side. Target of the work is to determine by experiments and theoretical models under which conditions DFB lasers can be used instead of more expensive ECL lasers. After careful characterization of lasers phase noise in terms of linewidth as a function of the mismatch between the optical paths of the signal and of the local oscillator, the performance of two laser technologies is investigated in the proposed transmission setup, showing that commercial DFB laser can be used, provided that the optical path mismatch between the two fibers is kept below 1.8 meter for 28 GBaud PM-QPSK and 0.8 meter for PM-16QAM modulation format in combination with a soft-decision forward error correction algorithm. After an experimental demonstration, we theoretically investigate the scalability laws of the proposed systems in different configuration flavours

Performance evaluation of coherent WDM PS-QPSK (HEXA) accounting for non-linear fiber propagation effects

Coherent-detection (CoD) permits to fully exploit the fourdimensional (4D) signal space consisting of the in-phase and quadrature components of the two fiber polarizations. A well-known and successful format exploiting such 4D space is Polarization-multiplexed QPSK (PM-QPSK). Recently, new signal constellations specifically designed and optimized in 4D space have been proposed, among which polarizationswitched QPSK (PS-QPSK), consisting of a 8-point constellation at the vertices of a 4D polychoron called hexadecachoron. We call it HEXA because of its geometrical features and to avoid acronym mix-up with PM-QPSK, as well as with other similar acronyms. In this paper we investigate the performance of HEXA in direct comparison with PM-QPSK, addressing non-linear propagation over realistic links made up of 20 spans of either standard single mode fiber (SSMF) or non-zero dispersion-shifted fiber (NZDSF). We show that HEXA not only confirms its theoretical sensitivity advantage over PM-QPSK in back-to-back, but also shows a greater resilience to non-linear effects, allowing for substantially increased span loss margins. As a consequence, HEXA appears as an interesting option for dual-format transceivers capable to switch on-the-fly between PM-QPSK and HEXA when channel propagation degrades. It also appears as a possible direct competitor of PM-QPSK, especially over NZDSF fiber and uncompensated links