Contribution à l'étude de fonctions optiques pour la régénération du signal dans les systèmes de transmission à haut débit

Abstract : Future optical high-bit-rate and long-haul links will need the use of simple and cost-effective devices to replace some of the existing optoelectronic repeaters in order to enhance the performance and reduce the cost. A key component is microcavity saturable absorber (SA), which is particularly interesting for this type of application. In the present thesis, we propose theoretical and experimental studies of all-optical regeneration for optical transmission systems. The motivation for the development of all-optical regeneration techniques is outlined in the chapter 1. A review of the main regeneration principles and techniques found in the literature is addressed. Chapter 2, we survey the used characterization techniques in order to evaluate the effciency of a regenerator. A simulator in this thesis is also developed and is used to analyze the regenerated links. In chapter 3, we investigate an all-optical 2R regenerator based on SA and self-phase modulation in fiber. An eight-channel SA with optimized optical coupling is described in this chapter. The WDM compatibility of this device is experimentally demonstrated in a 100-km recirculating loop. A minimum distance improvement ratio of 3.3 is obtained with all channels at a bit error rate (BER) of 10−4. This distance improvement efficiency is also achieved over a 13-nm optical bandwidth around 1 550 nm. Chapter 4 presents a novel SA used as an alternative solution for power limiting function. A new 2R regenerator architecture based on dual-stage SA devices is then studied. The first SA enhance the extinction ratio, the second one (novel power limiter AS) suppresses amplitude noise on high power levels ("1" level). Chapter 5 is devoted to the 3R regeneration based on 2R regeneration combined with synchronous modulation. The reshaping stage is realized by the 2R regenerator presented in Chapter 3. The all optical synchronous modulation is achieved by launching into the SA the optical clock delivered by an all-optical clock recovery device using mode-locked semiconductor lasers based on bulk and quantum-dash structures. The efficiency of the 3R device is evaluated for a 100-km recirculating loop at 42.7 Gbit/s. A distance improvement ratio of 22.5 (transmission distance of 18000 km) is obtained for a BER of 10−8. Finally, the last chapter considers the regeneration of phase-shift keying (PSK) signals. An optical PSK transmission system is mainly limited by the accumulation of linear and nonlinear phase noise. Linear phase noise results from amplified spontaneous emission produced by optical amplifiers. Where as nonlinear phase noise results from intra-channel and inter-channel nonlinearities such as self-phase modulation and cross-phase modulation that convert amplitude noise to phase noise. The novel SA presented in chapter 4 can suppress the amplitude noise and preserve the signal phase. Consequently, when it is used in a trans- mission link with high fiber-launched power, the SA reduces the amplitude noise, which is the origin of nonlinear phase noise, thus improving the system performance. A distance improvement ratio of 1.6 at BER of 10−4 is demonstrated in a recirculating loop.
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Physique [physics]. Université Rennes 1, 2010. Français
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Quang Trung Le. Contribution à l'étude de fonctions optiques pour la régénération du signal dans les systèmes de transmission à haut débit. Physique [physics]. Université Rennes 1, 2010. Français. 〈tel-00568932〉



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