Showing papers by "Antonio Mecozzi published in 1999"
TL;DR: In this paper, a theoretical analysis of the modulation response of a semiconductor laser amplifier is presented, where the role of the waveguide (scattering) loss is investigated in detail and is shown to influence the qualitative behavior of the response.
Abstract: We present a theoretical analysis of the modulation response of a semiconductor laser amplifier. We find a resonance behavior similar to the well-known relaxation oscillation resonance found in semiconductor lasers, but of a different physical origin. The role of the waveguide (scattering) loss is investigated in detail and is shown to influence the qualitative behavior of the response. In particular, it is found that a certain amount of waveguide loss may be beneficial in some cases. Finally, the role of the microwave propagation of the modulation signals is investigated and different feeding schemes are analyzed. The nonlinear transparent waveguide, i.e., an amplifier saturated to the point where the stimulated emission balances the internal losses, is shown to be analytically solvable and is a convenient vehicle for gaining qualitative understanding of the dynamics of modulated semiconductor optical amplifiers.
79 citations
TL;DR: In this paper, the first demonstration of compensation of optical-fiber dispersion using mid-span spectral inversion without frequency shift by a two-pump four-wave mixing configuration is presented.
Abstract: We report the first demonstration of compensation of optical-fiber dispersion using mid-span spectral inversion without frequency shift by a two-pump four-wave-mixing configuration. We achieve 120 km penalty-free transmission at 2.5 Gb/s over standard single-mode fiber using a directly modulated distributed-feedback laser.
28 citations
TL;DR: In this paper, the authors demonstrate that four-wave mixing in semiconductor optical amplifiers, with the use of two orthogonal-polarized pumps in a polarization diversity scheme, allows frequency conversion with efficiency independent of both signal polarization and conversion interval.
Abstract: In this letter, we demonstrate that four-wave mixing in semiconductor optical amplifiers, with the use of two orthogonal-polarized pumps in a polarization-diversity scheme, allows frequency conversion with efficiency independent of both signal polarization and conversion interval.
20 citations
TL;DR: In this article, a single semiconductor optical amplifier with two orthogonally polarized pumps was used for conjugate generation with efficiency independent of signal-conjugate detuning, and a comparison of the amplifier performance with mono-and bidirectional propagation was given.
Abstract: In this work, we demonstrate polarization-independent four-wave mixing using a single semiconductor optical amplifier. The result is obtained using a polarization-diversity scheme, in which all the injected fields are split by a polarization beam splitter and the two resulting patterns are injected counterpropagating in the amplifier. The use of two orthogonally polarized pumps allows a conjugate generation with efficiency also independent of the signal-conjugate detuning. A comparison of the amplifier performance with mono- and bidirectional propagation is given.
14 citations
08 Nov 1999
TL;DR: The physical processes in SOA's that are important in determining the speed of SOA based switches are discussed, which shall consider both devices based on incoherent processes, such as optically induced cross-gain and cross-phase modulation as well as devices employing coherent four-wave mixing.
Abstract: Several different semiconductor device structures for accomplishing all-optical signal processing have been proposed, but they nearly all employ the semiconductor optical amplifier (SOA) as a central element. In this talk we will discuss the physical processes in SOA's that are important in determining the speed of SOA based switches. We shall consider both devices based on incoherent processes, such as optically induced cross-gain and cross-phase modulation as well as devices employing coherent four-wave mixing.
10 citations
01 Jan 1999
TL;DR: In this article, the authors presented the theory of four-wave mixing in optical amplifiers and derived the rate equations from density matrix equations, and after coupling with the propagation equation for the field envelope and its phase, a rather general description of the fourwave mixing was obtained.
Abstract: The present chapter is devoted to presenting the theory of four-wave mixing in semiconductor optical amplifiers (SOAs). At first, a model describing the dynamics in terms of rate equations is developed. The rate equations are derived from density matrix equations, and after coupling with the propagation equation for the field envelope and its phase, a rather general description of the four-wave mixing is arrived at. In the limit of zero scattering loss, the model leads to a very simple description of the effects of four-wave mixing. In the succeeding sections we will concentrate on the advantages and draw-backs of some analytical models based on the coupled-mode theory and used to calculate the FWM performance of SOAs. In addition, the effects of amplified spontaneous emission (ASE) noise are considered. The theoretical models presented here should be of interest for all those performing experimental FWM investigations. Particular attention is given to the validity of the assumptions used in the models.
8 citations
28 May 1999
TL;DR: In this article, it was shown that the amplitude fluctuations due to the XPM can be converted to phase fluctuations in a regime of weak average normal dispersion; as a consequence, this conversion may provide a method to control XPM limitations.
Abstract: Summary form only given. Four wave mixing (FWM) and cross-phase modulation (XPM) processes are the most relevant impairments in wavelength division multiplexed (WDM) systems. The former causes generation of novel frequencies, the latter induces a phase shift on pulses crossing each other. In both effects the chromatic dispersion (GVD) of the fiber plays a significant role. Increasing the absolute value of the GVD, the efficiency of FWM effect decreases, but the XPM phase distortion is converted into intensity fluctuations. As a result, XPM is the main limitation for systems operating on step-index fibers. One method to limit XPM impairment is the periodical compensation of the GVD using dispersion managed (DM) links. Moreover, the DM technique improves the dispersion limited performance of each single channel, by propagating close to zero average GVD. In a previous work it was proved that nonlinear propagation in the regime of low normal dispersion may induce a amplitude-to-phase conversion of ASE noise. Clearly, this may lead to an improvement of the performance of IM-DD systems where the phase noise is discarded by the detecting photodiode. In analogy with the theory developed previously it can be numerically shown that in WDM DM links in which the pulses do not show significant strong shape distortion, the amplitude fluctuations due to the XPM can be converted to phase fluctuations in a regime of weak average normal dispersion; as a consequence this conversion may provide a method to control the XPM limitations.
4 citations
TL;DR: By varying the gain of the optical amplifier, a strong dependence of both conversion efficiency and signal-to-background ratio on pulse width and bit rate is found, which can be optimized for a specific amplifier gain.
Abstract: We investigate the saturation properties of four-wave mixing of short optical pulses in a semiconductor optical amplifier. By varying the gain of the optical amplifier, we find a strong dependence of both conversion efficiency and signal-to-background ratio on pulse width and bit rate. In particular, the signal-to-background ratio can be optimized for a specific amplifier gain. This behavior, which is coherently described in experiment and theory, is attributed to the dynamics of the amplified spontaneous emission, which is the main source of noise in a semiconductor optical amplifier.
4 citations
23 May 1999
TL;DR: In this article, a comparison between theory and experiment on the four wave mixing between trains of short pulses in semiconductor optical amplifiers is made. But the results of the comparison are limited to the case where the theory is able to explain all qualitative features seen in the experiment.
Abstract: Summary form only given. The authors report the first comparison between theory and experiment on the four wave mixing between trains of short pulses in semiconductor optical amplifiers. The theory is able to explain all qualitative features seen in the experiment.
08 Nov 1999
TL;DR: In this paper, it was shown that index dispersion in connection with the standard saturation of the medium due to carrier density changes, lead to ultrafast gain and index dynamics, and it is shown that these new contributions may dominate experimentally observed results.
Abstract: We show that index dispersion in connection with the standard (slow) saturation of the medium due to carrier density changes, lead to ultrafast gain and index dynamics. Analytical formulas are derived, and it is shown that these new contributions may dominate experimentally observed results.