|Abstract: ||The temporal characteristics and the spectral content of light can be manipulated and
modified by harnessing linear and nonlinear interactions with a dielectric medium. Optical
fibres provide an environment in which the tight confinement of light over long distances
allows the efficient exploitation of weak nonlinear effects. This has facilitated the
rapid development of high-power fibre laser sources across a broad spectrum of wavelengths,
with a diverse range of temporal formats, that have established a position of
dominance in the global laser market. However, demand for increasingly flexible light
sources is driving research towards novel technologies and an improved understanding
of the physical mechanisms and limitations of existing approaches.
This thesis reports a series of experiments exploring two topical areas of ongoing research
in the field of nonlinear fibre optics: mode-locked fibre lasers and fibre-based
supercontinuum light sources.
Firstly, integration of novel nano-materials with existing and emerging fibre-based
gain media allows the demonstration of ultrafast mode-locked laser sources across the
near-infrared in a conceptually simple, robust, and compact scheme. Extension to important
regions of the visible is demonstrated using nonlinear conversion.
Scaling of pulse energies in mode-locked lasers can be achieved by operating with
purely positive dispersion for the generation of chirped pulses. It is shown unequivocally,
through a direct measurement, that the pulses generated in ultra-longmode-locked lasers
can exist as highly-chirped dissipative soliton solutions of the cubic (and cubic-quintic)
Ginzburg Landau equation. The development of a numerical model provides a framework
for the interpretation of experimental observations and exposes unique evolution
dynamics in extreme parameter ranges. However, the practical limitations of the approach
are revealed and alternative routes towards achieving higher-energy are proposed.
Finally, an experimental and numerical study of the dependence of continuous-wave
pumped supercontinua on the coherence properties of the pump source shows an optimum
exists that can be expressed as a function of the modulation instability period. A
new and simplified model representing the temporal fluctuations expressed by continuous wave
lasers is proposed for use in simulations of supercontinua evolving from noise.
The implications of the experiments described in this thesis are summarised within
the broader context of a continued research effort.|