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Multi-impairment and multi-channel optical performance monitoring

Meflah, L.; (2008) Multi-impairment and multi-channel optical performance monitoring. Doctoral thesis, UCL (University College London). Green open access

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Next generation optical networks will evolve from static to dynamically reconfigurable architectures to meet the increasing bandwidth and service requirements. The benefits of dynamically reconfigurable networks (improved operations, reduced footprint and cost) have introduced new challenges, in particular the need for complex management which has put pressure on the engineering rules and transmission margins. This has provided the main drive to develop new techniques for optical performance monitoring (OPM) without using optical-to-electrical-to-optical conversions. When considering impairments due to chromatic dispersion in dynamic networks, each channel will traverse a unique path through the network thus the channels arriving at the monitoring point will, in general, exhibit different amounts of residual dispersion. Therefore, in a dynamic network it is necessary to monitor all channels individually to quantify the degradation, without the requirement of knowing the data path history. The monitoring feature can be used in conjunction with a dispersion compensation device which can either be optical or electrical or used to trigger real-time alarms for traffic re-routing. The proposed OPM technique is based on RF spectrum analysis and used for simultaneous and independent monitoring of power, chromatic dispersion (CD), polarisation mode dispersion (PMD) and optical signal-to-noise ratio (OSNR) in 40Gbit/s multi0channel systems. An analytical model is developed to describe the monitoring technique which allows the prediction of the measurement range. The experimental results are given for group velocity dispersion (GVD), differential group delay (DGD) and OSNR measurements. This technique is based on electro-optic down-conversion that simultaneously down-converts multiple channels, sharing the cost of the key components over multiple channels and making it cost effective for multi-channel operation. The measurement range achieved with this method is equal to 4742±100ps/nm for GVD, 200±4ps for DGD and 25±1dB for OSNR. To the knowledge of the author, these dispersion monitoring ranges are the largest reported to date for the bit-rate of 40Gbit/s with amplitude modulation formats.

Type:Thesis (Doctoral)
Title:Multi-impairment and multi-channel optical performance monitoring
Open access status:An open access version is available from UCL Discovery
UCL classification:UCL > School of BEAMS > Faculty of Engineering Science > Electronic and Electrical Engineering

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