Monitoring the Quality of Signal in Packet-Switched Networks Using Optical Correlators

The increasing demand in the Internet network for real-time multimedia data traffic with high quality of service (QoS) is pushing the limits of existing network structure. Optical packet switching (OPS) is considered as a possible technology for future telecommunication networks due to its compatibility with bursty traffic and efficient use of the network resources. But OPS brings about new challenges to the research in optical performance monitoring (OPM). In this scenario, each packet follows its own path along the network depending on the routing information contained in the label and thereby packets suffer from different signal degradations. Therefore, a definitive goal for OPM is to provide comprehensive signal quality information as part of QoS implementation to keep the level of QoS promised to customers. In this paper, a novel optical SNR (OSNR) monitoring technique based on the use of optical correlation is presented. A fiber Bragg grating-based correlator was constructed and used to experimentally demonstrate the successful correlation. Experiments performed on a 40 Gb/s system confirm the viability of this approach. By measuring statistics from the autocorrelation peak, the monitor is capable of direct OSNR monitoring with an error of less than 0.5 dB.