SOA - NOLM in Reflective Configuration for Optical Regeneration in High Bit Rate Transmission Systems

This paper presents a theoretical and experimental investigation of optical signal regeneration properties of a non-linear optical loop mirror using a semiconductor optical amplifier as the active element (SOA-NOLM). While this device has been extensively studied for optical time division demultiplexing (OTDM) and wavelength conversion applications, our proposed approach, based on a reflective configuration, has not yet been investigated, particularly in the light of signal regeneration. The impact on the transfer function shape of different parameters, like SOA position in the interferometer and SOA input optical powers, are numerically studied to appreciate the regenerative capabilities of the device.Regenerative performances in association with a dual stage of SOA to create a 3R regenerator which preserves the data polarity and the wavelength are experimentally assessed. Thanks to this complete regenerative function, a 100.000 km error free transmission has experimentally been achieved at 10 Gb/s in a recirculating loop. The evolution of Bit Error Rate for multiple pass into the regenerator and the polarization insensitivity demonstration to input data are presented

FROG characterisation of SOA-based wavelength conversion using XPM in conjunction with shifted filtering up to line rates of 80 GHz

The work we present here builds on recent work where we obtained 80 Gb/s error free performance using cross phase modulation (XPM) in an SOA in conjunction with a blue shifted bandpass filter. Here we present a detailed characterisation of this wavelength conversion scheme using a Frequency Resolved Optical Gating (FROG) measurement scheme for both red and blue shifted filtering. This type of characterisation has not been provided before to the best of our knowledge and is an important analysis firstly to achieve a full understanding of the gain and phase dynamics exploited by the wavelength conversion scheme presented and secondly to design a filter so that an optimum performance can be obtaine

Syndecan-3 and syndecan-4 are enriched in Schwann cell perinodal processes

BACKGROUND: Nodes of Ranvier correspond to specialized axonal domains where voltage-gated sodium channels are highly concentrated. In the peripheral nervous system, they are covered by Schwann cells microvilli, where three homologous cytoskeletal-associated proteins, ezrin, radixin and moesin (ERM proteins) have been found, to be enriched. These glial processes are thought to play a crucial role in organizing axonal nodal domains during development. However, little is known about the molecules present in Schwann cell processes that could mediate axoglial interactions. The aim of this study is to identify by immunocytochemistry transmembrane proteins enriched in Schwann cells processes that could interact, directly or indirectly, with axonal proteins. RESULTS: We show that syndecan-3 (S3) and syndecan-4 (S4), two proteoglycans expressed in Schwann cells, are enriched in perinodal processes in rat sciatic nerves. S3 labeling was localized in close vicinity of sodium channels as early as post-natal day 2, and highly concentrated at nodes of Ranvier in the adult. S4 immunoreactivity accumulated at nodes later, and was also prominent in internodal regions of myelinated fibers. Both S3 and S4 were co-localized with ezrin in perinodal processes. CONCLUSIONS: Our data identify S3 and S4 as transmembrane proteins specifically enriched in Schwann cell perinodal processes, and suggest that S3 may be involved in early axoglial interactions during development

Analysis of bit rate dependence up to 80 Gbit/s of a simple wavelength converter based on XPM in a SOA and a shifted filtering

This paper provides the analysis of wavelength converted pulses obtained with a simple semiconductor optical amplifier (SOA)-based wavelength conversion scheme, which exploits cross phase modulation (XPM) in an SOA in conjunction with shifted filtering. The analysis includes experimental measurements of the back-to-back system performances as well as frequency-resolved optical gating (FROG) characterisations of the wavelength converted pulses. These measurements are implemented at different bit rates up to 80 Gbit/s and for both red and blue-shifted filtering, particularly showing different patterning effect dependencies of red and blue-shifting techniques. This analysis is developed by the addition of a numerical study which corroborates the experimental results. A further understanding of the different performances of red and blue filtering techniques, presented in the literature, can thus be proposed. The placement of the filter to undertake red-shifted filtering (RSF) allows us to achieve very short pulse widths but high bit rate operation is limited by pattern effects. The blue-shifted filtering (BSF) technique shows optimum performance as regards to patterning effects even if the wavelength converted pulses can be larger

La Boucle à Recirculation Courte: Un nouvel outil pour evaluer une ligne de transmission régénérée optiquement

session orale 31 « Systèmes et réseaux de télécommunications » [Ma31]National audienceNous présentons une technique pour caractériser la cascadabilité et la résistance au bruit d'un régénérateur optique. L'impact du rapport signal sur bruit optique sur les performances du régénérateur ainsi que l'efficacité de la régénération sont évalués au débit de 42,6 Gbit/s

Impact du décalage du filtre sur les performances d'un convertisseur en longueur d'onde à base de SOA et filtrage décalé

session 4 «Systèmes et réseaux de télécommunications optiques » [S4O1]National audienceNous analysons l'efficacité d'un convertisseur en longueur d'onde composé simplement d'un amplificateur à semi-conducteurssuivi d'un filtre et qui n'inverse pas la polarité du signal entre entrée et la sortie. Pour cela des mesures de taux d'erreurs binaires ainsi que de profils temporels des impulsions de sortie via un FROG (Frequency Resolved Optical Gating) sont réalisées pour différents débits allant jusqu'à 80 Gbit/s

Distributing Automata for Asynchronous Networks of Processors

This paper addresses the problem of distributed program synthesis. In the first part, we formalize the distribution process and prove its correctness, i.e. that the initial centralized program's behavior is equivalent to the corresponding distributed's one. In order to achieve that, we first represent the program by a finite transition system, labeled by the program's actions. Then we derive an independence relation over the actions from the control and data dependencies. This leads to represent the program by an order-automaton, whose transitions are labeled partial orders coding for an action and its dependencies with other actions. In the second part, we show how such an order-automaton can be practically used to derive a distributed program