Véronique Moeyaert

Optical layer monitoring in Passive Optical Networks (PONs): A review

Motivations, challenges and requirements of optical layer monitoring in PONs are discussed. An exhaustive review of monitoring systems is given considering both time-division multiplexed PON (TDM-PON) and wavelength-division multiplexed PON (WDM-PON) cases.

Novel Monitoring Technique for Passive Optical Networks Based on Optical Frequency Domain Reflectometry and Fiber Bragg Gratings

An efficient monitoring method having a very short measurement time (a few seconds) is proposed. The equal-length branches can be effectively monitored, but also the information of temperature at any place in the network can be obtained. The feasibility of this technique is experimentally demonstrated.

Review of Trackside Monitoring Solutions: From Strain Gages to Optical Fibre Sensors

A review of recent research on structural monitoring in railway industry is proposed in this paper, with a special focus on stress-based solutions. After a brief analysis of the mechanical behaviour of ballasted railway tracks, an overview of the most common monitoring techniques is presented. A special attention is paid on strain gages and accelerometers for which the accurate mounting position on the track is requisite. These types of solution are then compared to another modern approach based on the use of optical fibres. Besides, an in-depth discussion is made on the evolution of numerical models that investigate the interaction between railway vehicles and tracks. These models are used to validate experimental devices and to predict the best location(s) of the sensors. It is hoped that this review article will stimulate further research activities in this continuously expanding field.

Optical frequency domain reflectometry: A review

In this paper, we discuss the operation principles, challenges and application areas of optical frequency domain reflectometry technique. A review of OFDR systems is given considering both Incoherent-OFDR and Coherent-OFDR groups. Results obtained by different research groups are compared in terms of performance characteristics, and future perspectives. Recent progresses obtained within our laboratory are also presented.

A PC-based method for the localisation and quantization of faults in passive tree-structured optical networks using the OTDR technique

The method presented showed that the optical time domain reflectometry can be used to facilitate the maintenance of multistaged tree-structured passive optical networks at a lowcost. This method has been implemented in a user-friendly software, and the results obtained proved its effectiveness. We also showed that it is possible to estimate the loss of a fault only on the basis of OTDR traces acquired at the networks head despite the fact that such traces result in the combination of the reflected and backscattered signals coming from the different optical paths.

Complete Analysis of Multireflection and Spectral-Shadowing Crosstalks in a Quasi-Distributed Fiber Sensor Interrogated by OFDR

We present the analysis of a quasi-distributed fiber sensor based on the concatenation of identical low-reflective fiber Bragg gratings (FBGs) taking into account both multireflection and spectral-shadowing crosstalks. This allows obtaining more realistic values of the design parameters such as the maximum number of sensing points, the reflectivity of the gratings, and the distance between the sensing points.

Analysis of the MAC performances in 802.11g radio-over-fiber systems

This paper investigates the performance when the IEEE 802.11g standard is used in a radio-over-fiber (RoF) network. We report that the IEEE 802.11g throughput may be dramatically deteriorated in RoF systems. We then show the possibility to adapt the slottime parameter in order to improve the IEEE 802.11g performances in RoF networks.

Localization and quantification of reflective events along an optical fiber using a bi-directional TRA technique.

We report on the theory and the implementation of a novel approach for the detection and localization of a reflective event along a fiber link. By launching a continuous-wave signal into both fiber ends and by analyzing the transmitted and reflected/backscattered optical powers, it is possible to localize an optical event and to quantify the induced insertion and return losses simultaneously. The novel idea of utilizing bi-directional measurement allows the localization of both reflective and non-reflective events. Theoretical and experimental studies show that for a 10 km-long single mode fiber, the localization accuracy can be in the range of 5.0 m.

Multi-wavelength transmission-reflection analysis for fiber monitoring

We propose and implement a novel approach based on multi-wavelength Transmission-Reflection Analysis (MW-TRA) technique for monitoring lossy events (e.g. disconnected connectors, fiber breaks and fiber bendings) along an optical fiber link. By launching un-modulated continuous-wave lights carried by different wavelengths into the fiber and measuring their transmitted and reflected/backscattered optical powers, our proposed MW-TRA scheme is able to localize any lossy event (including both reflective and non-reflective) and to quantify the corresponding insertion and return losses with high accuracy.

Fast and simple fault monitoring for long-reach passive optical networks

We propose a fast and simple monitoring system based on multi-wavelength bi-directional transmission reflection analysis approach for long-reach passive optical networks. Both experimental and simulation results have demonstrated the proposed system can reach high accuracy for fault localization.