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The management of wavelength routed optical mesh networks is complex with many potential light path routes and numerous physical layer impairments to transmission performance. This complexity can be reduced by applying the ideas of abstraction from computer science where different equipment is described in the same basic terms. The noise-to-signal ratio can be used as a metric to describe the quality of transmission performance of a signal propagated through a network element and accumulates additively through a sequence of such elements allowing the estimation of end-to-end performance. This study aims to explore the robustness of the noise-to-signal ratio metric in an installed fibre infrastructure. We show that the abstracted noise-to-signal ratio is independent of the observers and their location. We confirm that the abstracted noise-to-signal ratio can reasonably predict the performance of light-paths subsequently set in our network. Having a robust network element abstraction that can be incorporated into routeing engines allows the network management controller to make decisions on the most effective way to use the network resources in terms of the routeing and data coding format. [ABSTRACT FROM AUTHOR]

High-speed broadband services require optical fibres in access networks, in which multiple subscribers are connected to service providers, to satisfy the continuously growing bandwidth demand. The primitive signaling scheme used in access networks enables the use of low-cost equipment but diminishes the bandwidth available to end-users. Thus, current technology will be unable to support future broadband demands. Coherent communication systems offer significantly improved power- and bandwidth-efficiency, but require fundamental simplifications to become economically viable for access networks. Here, we demonstrate a promising simplified coherent receiver exhibiting a robust performance against polarisation fluctuations over an installed fibre network. It enables the realisation of high-order modulation formats and offers high sensitivities, achieving a four-fold increase in the supported number of subscribers and approximately doubling the transmission distance compared to the recently standardized access technology. The proposed solution indicates that digital coherent technology can be feasible and transform the access networks, enabling ubiquitous new services and applications with uncontended, multi-gigabits/user broadband connections. [ABSTRACT FROM AUTHOR]

A new, simplified analytical model for the calculation of the signal-to-noise ratio (SNR) in multiwavelength erbium-doped fibre amplifier (EDFA) cascades is presented. Comparisons with numerical results give excellent agreement, confirming the validity of this model and its significance for optimising system parameters. [ABSTRACT FROM AUTHOR]

We describe the performance of a 100 channel free-space concave grating demultiplexer with 1dB transmission passband of ±7GHz (FWHM 14–22GHz). The influence of optical aberrations and defocusing on the transmission spectrum is demonstrated. Crosstalk between neighbouring channels separated by >0.3nm is lower than −25dB and no penalty due to crosstalk is observed using 2.6Gbit/s directly modulated DFB lasers. Penalty-free transmission through a cascade of 30 demultiplexers is demonstrated in an optical fibre recirculating loop experiment, and the permitted tolerances on the laser frequency misalignments for a larger number of cascaded demultiplexers are investigated. [ABSTRACT FROM AUTHOR]

There has been a lot of interest in the applications of the gain in the non-linear stimulated Brillouin scattering (SBS) process for all-optical amplification at low pump powers. The power levels at which SBS thresholds are observed can be greatly reduced in high-finesse, single-mode, all-fibre ring resonators. In this work a simple model which describes the transient generation of the SBS in such a resonator is developed. The model accounts for pump depletion, describes the build-up of the amplified spontaneous emission, and can be used to predict the Brillouin threshold in terms of the practical resonator and fibre parameters. Good agreement is reported between experimentally measured data and the theoretical results from this model. By operating this device below threshold, a signal at the Stokes frequency can be amplified. A detailed evaluation of the performance characteristics of such Brillouin amplifiers in terms of the signal gain, signal-to-noise ratio, time response of the device and gain saturation is presented. [ABSTRACT FROM AUTHOR]