TABLE OF CONTENTS There are two main sources of error that affect the soliton system, fluctuations of the pulse energies and of their arrival times. At each amplifier, the addition of the ASE noise changes the energy, central frequency, mean time, and phase of the solitons in statistically random ways. The changes in mean time and phase are of little importance in the present context. The other two changes can be analyzed separately. We shall focus on the energy fluctuations in this section, and on the frequency changes and the resultant jitter in arrival times in the next.
The energy fluctuations are quite similar to those that occur in a linear system. The argument is as follows: The system is effectively linear over short distances, so there is no difference in the way the noise field is injected into the system. The only difference in the soliton system is that the energy changes of first order in the noise field (the so-called signal spontaneous noise) are captured by the solitons, which then reshape themselves as they propagate. This reshaping is done with no significant change in energy. Thus the energy fluctuations at the receiver are like those that would occur if the system were linear and dispersion free.
To evaluate the errors incurred by the energy fluctuations, some model detector must be chosen. For simplicity we shall assume that the detector consists first of an optical filter of bandwidth B 0, followed by a photodetector,...
