S. Benedetto

Suppression of spurious tones induced by the split-step method in fiber systems simulation

Numerical approximations involved in solving the nonlinear Schrodinger equation using the split-step method may cause the generation of spurious spectral peaks which can be seen as fictitious four-wave mixing. In this letter, we present a new method for reducing and controlling such simulation artifacts by properly choosing the spatial step size.

New analytical results on fiber parametric gain and its effects on ASE noise

Parametric gain (PG) in optical fibers may substantially enhance ASE noise, especially in long-haul amplified systems. We present new closed-form analytical results that permit to accurately characterize the effects of PG on ASE noise, as well as the interplay of PG and ASE noise with fiber dispersion in both the anomalous and normal dispersion regions. We introduce the concept of a PG transfer matrix that allows the easy analytical evaluation of ASE noise enhancement over chains of amplified fiber spans.

Theory of polarization spreading techniques. I

Presents an analysis of a series of techniques grouped under the denomination polarization spreading, the intent of which is that of making the performance of a coherent optical receiver insensitive to the polarization transformations occurring along the optical fiber, without resorting to polarization compensation or control. The principle on which Polarization spreading operates is that of spreading the signal power over different states of polarization, so that heterodyning of at least half of the optical incident bit energy is always ensured. The main results obtained concern a condition that guarantees the maximum heterodyned signal energy, some classes of spreading waveforms satisfying the above condition, the derivation of the structure and the performance of optimum receivers in Gaussian noise. The results encompass most of the binary optical coherent modulation schemes proposed and experimented, such as ASK, FSK and DPSK. >

A LiNbO3 modulator for binary and multilevel polarization modulation

The modulation of the state of polarization (SOP) of light has been recently proposed for transmission of information on optical fibers.1-4 Polarization-shift keying (POLSK) is suitable for both coherent and direct-detection (DD) systems. In either case, both binary and multilevel schemes are possible.

System impact of fiber parametric gain in long-haul optical links

We study the effect of parametric gain in long-haul, optically amplified links. We started by introducing a formalism required to evaluate the spectral enhancement of amplified spontaneous emission noise due to the Kerr-effect non-linear interaction between the signal and noise. These results are then used to evaluate parametric gain-induced performance degradation on the system Q value. Finally we analyze long-haul links at 10 Gb/s using different dispersion compensation maps by evaluating the maximum reachable distance in each configuration. We show that less frequent dispersion compensation improves the system performance.