Marc Stephens

Bio: Marc Stephens is an academic researcher from Aston University. The author has contributed to research in topics: Optical amplifier & Wavelength-division multiplexing. The author has an hindex of 15, co-authored 70 publications receiving 1028 citations. Previous affiliations of Marc Stephens include University of Bristol & Coventry Health Care.

WASPNET: a wavelength switched packet network

Abstract: WASPNET is an EPSRC-funded collaboration between three British Universities: the University of Strathclyde, Essex University, and Bristol University, supported by a number of industrial institutions. The project which is investigating a novel packet-based optical WDM transport network-involves determining the management, systems, and devices ramifications of a new network control scheme, SCWP, which is flexible and simplifies optical hardware requirements. The principal objective of the project is to understand the advantages and potential of optical packet switching compared to the conventional electronic approach. Several schemes for packet header implementation are described, using subcarrier multiplexing, separate wave lengths, and serial transmission. A novel node design is introduced, based on wavelength router devices, which reduce loss, hence reducing booster amplifier gain and concomitant ASE noise. The fabrication of these devices, and also wavelength converters, are described. A photonic packet switching testbed is detailed which will allow the ideas developed within WASPNET to be tested in practice, permitting the practical problems of their implementation to be determined.

Exceeding the nonlinear-shannon limit using raman laser based amplification and optical phase conjugation

Abstract: We demonstrate that a combination of Raman laser based amplification and optical phase conjugation enables transmission beyond the nonlinear-Shannon limit. We show nonlinear compensation of 7x114Gbit/s DP-QPSK channels, increasing system reach by 30%.

4 Tb/s Transmission Reach Enhancement Using 10 × 400 Gb/s Super-Channels and Polarization Insensitive Dual Band Optical Phase Conjugation

Abstract: In this paper, we experimentally demonstrate the benefit of polarization insensitive dual-band optical phase conjugation for up to ten 400 Gb/s optical super-channels using a Raman amplified transmission link with a realistic span length of 75 km. We demonstrate that the resultant increase in transmission distance may be predicted analytically if the detrimental impacts of power asymmetry and polarization mode dispersion are taken into account.

Demonstration of ultrafast all-optical wavelength conversion utilizing birefringence in semiconductor optical amplifiers

Abstract: High-extinction-ratio wavelength conversion has been demonstrated in a semiconductor optical amplifier using a mixture of cross-gain and cross-phase modulation in a polarization rotation technique. 40-ps-wide pulses at 1311 nm have been generated using 47-ps, 5.7-mW peak-power input pulses at 1300 nm. Excellent agreement with experiment has been obtained using a computer model.

Reduction of Nonlinear Intersubcarrier Intermixing in Coherent Optical OFDM by a Fast Newton-Based Support Vector Machine Nonlinear Equalizer

Abstract: A fast Newton-based support vector machine (N-SVM) nonlinear equalizer (NLE) is experimentally demonstrated, for the first time, in 40 Gb/s 16-quadrature amplitude modulated coherent optical orthogonal frequency division multiplexing at 2000 km of transmission. It is shown that N-SVM-NLE extends the optimum launched optical power by 2 dB compared to the benchmark Volterra-based NLE. The performance improvement by N-SVM is due to its ability of tackling both deterministic fiber-induced nonlinear effects and the interaction between nonlinearities and stochastic noises (e.g., polarization-mode dispersion). An N-SVM is more tolerant to intersubcarrier nonlinear crosstalk effects than Volterra-based NLE, especially when applied across all subcarriers simultaneously. In contrast to the conventional SVM, the proposed algorithm is of reduced classifier complexity offering lower computational load and execution time. For a low C -parameter of 4 (a penalty parameter related to complexity), an execution time of 1.6 s is required for N-SVM to effectively mitigate nonlinearities. Compared to conventional SVM, the computational load of N-SVM is ∼6 times lower.

Advances in photonic packet switching: an overview

Abstract: The current fast-growing Internet traffic is demanding more and more network capacity every day. The concept of wavelength-division multiplexing has provided us an opportunity to multiply network capacity. Current optical switching technologies allow us to rapidly deliver the enormous bandwidth of WDM networks. Photonic packet switching offers high-speed, data rate/format transparency, and configurability, which are some of the important characteristics needed in future networks supporting different forms of data. In this article we present some of the critical issues involved in designing and implementing all-optical packet-switched networks.

Optical Packet and Burst Switching Technologies for the Future Photonic Internet

Abstract: This paper reviews advanced optical burst switching (OBS) and optical packet switching (OPS) technologies and discusses their roles in the future photonic Internet. Discussions include optoelectronic and optical systems technologies as well as systems integration into viable network elements (OBS and OPS routers). Optical label switching (OLS) offers a unified multiple-service platform with effective and agile utilization of the available optical bandwidth in support of voice, data, and multimedia services on the Internet Protocol. In particular, OLS routers with wavelength routing switching fabrics and parallel optical labeling allow forwarding of asynchronously arriving variable-length packets, bursts, and circuits. By exploiting contention resolution in wavelength, time, and space domains, the OLS routers can achieve high throughput without resorting to a store-and-forward method associated with large buffer requirements. Testbed demonstrations employing OLS edge routers show high-performance networking in support of multimedia and data communications applications over the photonic Internet with optical packets and bursts switched directly at the optical layer

The application of optical packet switching in future communication networks

Abstract: Telecommunication networks are experiencing a dramatic increase in demand for capacity, much of it related to the exponential takeup of the Internet and associated services. To support this demand economically, transport networks are evolving to provide a reconfigurable optical layer which, with optical cross-connects, will realize a high-bandwidth flexible core. As well as providing large capacity, this new layer will be required to support new services such as rapid provisioning of an end-to-end connection under customer control. The first phase of network evolution, therefore, will provide a circuit-switched optical layer characterized by high capacity and fast circuit provisioning. In the longer term, it is currently envisaged that the bandwidth efficiency associated with optical packet switching (a transport technology that matches the bursty nature of multimedia traffic) will be required to ensure economic use of network resources. This article considers possible network application scenarios for optical packet switching. In particular, it focuses on the concept of an optical packet router as an edge network device, functioning as an interface between the electronic and optical domains. In this application it can provide a scalable and efficient IP traffic aggregator that may provide greater flexibility and efficiency than an electronic terabit router with reduced cost. The discussion considers the main technical issues relating to the concept and its implementation.

An Overview on Application of Machine Learning Techniques in Optical Networks

Abstract: Today’s telecommunication networks have become sources of enormous amounts of widely heterogeneous data. This information can be retrieved from network traffic traces, network alarms, signal quality indicators, users’ behavioral data, etc. Advanced mathematical tools are required to extract meaningful information from these data and take decisions pertaining to the proper functioning of the networks from the network-generated data. Among these mathematical tools, machine learning (ML) is regarded as one of the most promising methodological approaches to perform network-data analysis and enable automated network self-configuration and fault management. The adoption of ML techniques in the field of optical communication networks is motivated by the unprecedented growth of network complexity faced by optical networks in the last few years. Such complexity increase is due to the introduction of a huge number of adjustable and interdependent system parameters (e.g., routing configurations, modulation format, symbol rate, coding schemes, etc.) that are enabled by the usage of coherent transmission/reception technologies, advanced digital signal processing, and compensation of nonlinear effects in optical fiber propagation. In this paper we provide an overview of the application of ML to optical communications and networking. We classify and survey relevant literature dealing with the topic, and we also provide an introductory tutorial on ML for researchers and practitioners interested in this field. Although a good number of research papers have recently appeared, the application of ML to optical networks is still in its infancy: to stimulate further work in this area, we conclude this paper proposing new possible research directions.

Techniques for optical packet switching and optical burst switching

Abstract: Wavelength-division multiplexing appears to be the solution of choice for providing a faster networking infrastructure that can meet the explosive growth of the Internet. Several different technologies have been developed so far for the transfer of data over WDM. We survey two new technologies which are still in the experimental stage-optical packet switching and optical burst switching-and comment on their suitability for transporting IP traffic.