Showing papers by "Antonio Mecozzi published in 2001"

Cancellation of timing and amplitude jitter in symmetric links using highly dispersed pulses

Abstract: We study the properties of symmetric dispersion compensation in optical links using highly dispersed pulse transmission. We show analytically that by splitting the dispersion compensation equally between the input and output of the link, complete cancellation of the timing and amplitude jitter can be obtained in systems where the power profile is symmetric about the center. We explain the dynamics of this cancellation and show, theoretically and experimentaily, that with practical system parameters, symmetric compensation may lead to a considerable improvement in performance.

On the capacity of intensity modulated systems using optical amplifiers

Abstract: We study the information capacity and the information density of communication systems using optical amplifiers, in the direct detection intensity modulation case. Our results are compared with Shannon's formula for coherent detection, where we find that in the relevant range of parameters the information density of intensity modulated systems is equal to one half of the density of coherent systems minus 1 bit/s/Hz. We show that with typical values of optical signal-to-noise ratio of the order of 20 dB, multilevel signaling can increase the information density by no more than a factor of 3.5 relative to binary modulated systems. The highest information density is obtained with a symmetric optical spectrum and it cannot be improved by removing one sideband as in the single sideband modulation case.

The Roles of Semiconductor Optical Amplifiers in Optical Networks

Abstract: Optical amplifiers have played a leading role in the evolution of telecommunications over the course of the past decade. What would the world of telecommunications look like if optical amplifier technology had not been developed? For a start, wavelength-division multiplexing (WDM) would be impractical: At every repeating station the signal would have to be demultiplexed, electronically regenerated, and retransmitted. In this scenario, multiple fibers—rather than multiple wavelengths— would probably be the most economical way to increase transmission system capacity.Cost per bit would be much higher than is the case for WDM systems. This added expense would most certainly have limited the growth of the Internet, since its market penetration is primarily due to transmission bandwidth availability and low connection costs.

Limits on the spectral efficiency of intensity modulated direct detection systems with optical amplifiers

Abstract: We study the information capacity and the spectral efficiency of communication systems with optical amplifiers, in the direct detection intensity modulation case. We show that with typical values of OSNR of the order of 20 dB, multilevel signaling can increase the spectral efficiency by no more than a factor of 3.5 relative to binary modulated systems. The highest spectral efficiency is obtained with a symmetric optical spectrum, and it cannot be improved by removing one sideband as in the single sideband modulation case.

Modulation scheme for tedons

Abstract: 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 described. For example, the method for increasing transmission distance and transmission data rate of a fiber optical communications link using tedons includes the steps of encoding a data signal to be transmitted using an encoding scheme that reduces a number of ones in the data signal, transmitting the encoded data signal over the fiber optical communications link, receiving the encoded data signal and decoding the encoded data signal.

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

Abstract: 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:

The interplay between nonlinear effects in modern optical communications systems

Abstract: Summary form only given. The authors review the guidelines for the design of modern optical communications systems, considering primarily the penalties and limitations posed by nonlinear effects in optical fibers. In WDM systems, nonlinear optical effects are traditionally divided into two categories. The first consists of intra-channel impairments where fiber nonlinearities interact with the transmitted waveform in a way that results in self imposed distortions, a mechanism known as self phase modulation. The second category consists of inter-channel effects, where the distortions experienced by one channel result from the propagation of other channels that are transmitted at other optical frequencies, mediated by fiber nonlinearities. The main nonlinear mechanisms that belong to this category are four-wave mixing, cross-phase modulation and stimulated Raman scattering.