Small-signal power transient modelling and regulation in Raman amplified optical fibre links

Abstract

A Raman amplifier is a type of optical amplifier that finds application in long-haul wavelength division multiplexed optical communications systems. Despite the potentially complicated nonlinear and distributed nature of the optical power dynamics that can arise in Raman amplified optical fibre links, it is shown that a number of simple modelling approaches point towards the applicability of low-order models that can satisfactorily capture the small-signal dynamics of such links in the neighbourhood of fixed set-points. Based on this observation, a simple modelling and linear control design procedure is presented with the objective of synthesising finite-dimensional feedback controllers that can achieve small-signal power transient regulation across a range of optical signal wavelengths. The application of this procedure is shown to yield satisfactory closed-loop performance and robustness in a specific simulation example.

Keywords:

• optical communications
• backward pumped Raman amplifiers
• transient control
• nonlinear PDEs
• spatial discretisation
• linearisation
• model order reduction
• ℋ_∞-loopshaping

Acknowledgement

This research is partially funded by ARC Grant DP0880494 and AFOSR Grant FA2386-09-1-4111.