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Optical switching & signal processing

The ultimate aim of this programme is to remove ultrafast electronics from communications systems. The inherently high speeds of many all-optical processes may be harnessed to produce new non-electrical components and techniques for very fast signal manipulation and processing. We have a team working on the modelling, design and demonstration of systems and sub-systems for application in all-optical networks. Our approach is to accept the digital nature of the signal from the outset and to look for ways of manipulating channels at the bit level rather than switching in an analogue fashion as in optical cross connects. This has the advantage of eliminating impairments due to analogue mixing processes and of building in regeneration as a fundamental operation rather than a system add-on. Devices for switching, data header recognition, multiplexing, and memories are pursued using fibre and semiconductor devices.

We are also looking at the potential for these ultrafast all-optical techniques to allow us to develop better instrumentation using techniques such as temporal microscopy which allows us to expand in time short pulses.
  • Bit serial optical computation
  • All-optical switching
  • Optical memory and buffering

Problems:


  • Nonlinear transmission
  • Crosstalk
  • Four Wave Mixing
nonlinear 1

The Kerr effect in optical fibres will cause degradation of the system bit error rate if you simply ignore it and keep increasing the signal power.

Saturation of the inversion in semiconductor amplifiers can cause many unwanted signal effects.



Solutions:

  • Solitons
  • Optical switching
  • Optical Regeneration
  • Raman amplification
  • Pulse shaping
nonlinear2

The intensity dependent refractive index in optical fibres can be used to create self-sustaining pulses called solitons.

It can also be used to create an all-optical switch as well as Raman amplification, signal regeneration and pulsed lasers.

The understanding and mastering of nonlinear physical systems has the potential to enable a new generation of engineering concepts. Our research is at the interface between fundamental nonlinear science and practical applications in fibre optics and photonics.

Key Publications:

1 Sonia Boscolo and Christophe Finot, “Nonlinear Pulse Shaping in Fibres for Pulse Generation and Optical Processing,” International Journal of Optics, vol. 2012, Article ID 159057, 14 pages, 2012. doi:10.1155/2012/159057

2 B. Bale, S. Boscolo, K. Hammani, and C. Finot, "Effects of fourth-order fiber dispersion on ultrashort parabolic optical pulses in the normal dispersion regime," J. Opt. Soc. Am. B  28, 2059-2065 (2011).

3Sonia Boscolo  and Sergei K. Turitsyn Intermediate asymptotics in nonlinear optical systems Phys. Rev. A 85, 043811 (2012)


Contact: Keith Blow; k.j.blow@aston.ac.uk, Sonia Boscolo; s.a.boscolo@aston.ac.uk

Employable Graduates; Exploitable Research