All-optical signal regeneration using four-wave mixing

Abstract

All-optical signal processing schemes are being studied as promising candidates for adoption in future optical transmission systems, where they are hoped to offer benefits such as ultra-fast signal processing, reduced energy consumption and in some cases, multi-channel processing, supporting the deployment of new techniques such as optical burst switching and software defined networks.

The topic of this thesis is the all-optical phase and amplitude regeneration of complex signals using four-wave mixing (FWM). Many schemes for all-optical signal regeneration which have so far been demonstrated expose a signal to some undesirable concomitant distortion during regeneration, grossly limiting their practicability. Therefore, the work in this thesis focuses upon eliminating these undesirable effects and pursuing the development of regenerators possessing more ideal performance.

To this end, an amplitude preserving phase regenerator is first demonstrated using a phase sensitive amplifier (PSA) which functions through the use of an additional phase harmonic beyond that commonly used. The conclusions of this are extended to show that, given a means to coherently add a large number of phase harmonics of a signal, the phase transfer function of a PSA may be tailored exactly as pleased using a method similar to Fourier analysis.

Adoption of an exact solution to degenerate FWM allows for the demonstration of phase preservation in a saturated, pump-degenerate FWM-based amplitude regenerator, enabled by adopting a high pump to signal power ratio. Understanding of the phase noise processes present in this amplitude regenerator leads to an alternative scheme for phase preservation being demonstrated, which functions by predistorting the signal using optical nonlinearities, before amplitude squeezing.

This technique is then combined with a novel, single stage, wavelength converting idler-free PSA, to realise a system which is capable of regenerating both the phase and amplitude of a signal, and, by making use of the conjugating nature of both stages, allows for the negation of nonlinearity induced phase distortion between the two stages to realise a system which is greater than the sum of its two parts.

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Identifiers

ORCID for Kyle Bottrill: orcid.org/0000-0002-9872-110X

ORCID for Periklis Petropoulos: orcid.org/0000-0002-1576-8034

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