Computational Nonlinear Optics

We are currently looking for postgraduate students in the general area of theory and modelling of nonlinear optical systems. Close collaboration with experimental groups is expected and joint theoretical/experimental projects are also available. Specifically, we propose the following research topics.

1. Short-pulse propagation in large-core fibres

High-power laser pulses propagating in optical fibres experience strong nonlinear effects which can be exploited for spectral and temporal pulse shaping, leading for example to supercontinuum generation and applications in precision spectroscopy (Nobel Prize 2005). In large-core, multimode fibres novel effects have recently been reported, e.g. we observed the generation of RGB light from a green laser source. However, the modelling of such multimode nonlinear effects is still a largely unexplored area. The project will aim to enhance our understanding of these novel effects using theoretical and numerical models, ideally in conjuncture with experiments:

• Nonlinear optical effects in multimode holey fibres.
• Supercontinuum generation in multimode standard optical fibres.
• Optimisation of fibre design for the generation of specific light spectra.

2. Nonlinear optics in non-glass waveguides

Nonlinear propagation effects on laser pulses can be tailored over many orders of magnitudes when materials other than glasses are employed. One particularly exciting possibility is silicon photonics which offers hugely increased nonlinearities and a range of additional effects related to the semiconductor electronic properties.

Gas-filled capillaries or holey fibres, on the other hand, exhibit extremely weak nonlinearities. However, with sufficient pulse intensities novel regimes of nonlinear effects can be accessed. For example, ionisation and subsequent plasma recombination can generate intensive bursts of X-rays.

Investigations of nonlinear effects in superconductor or gas-filled waveguides are currently largely driven by experiments, with modelling of related effects still in its infancy. The project will address some of the modelling issues in close collaboration with experiments:

• Two-photon absorption and free carrier effects in short-pulse propagation.
• Active and passive spectral manipulation in semiconductor waveguides.
• Laser-induced ionisation and plasma effects in gas-filled capillaries and holey fibres.

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For details of how to apply please click here

Click here for a full list of projects for 2008.