|dc.contributor.advisor||Hall, Professor Denis R.||
|dc.contributor.advisor||Baker, Professor Howard J.||
|dc.description.abstract||This thesis addresses the strong need for efficient and compact techniques for brightness
enhancement of laser diode arrays and responds to the challenges created for high
performance optics and techniques for laser characterisation.
A novel optical inter-leaving method for a 7-bar stack of single-mode emitters,
providing a nearly 2-fold improvement in the slow axis beam parameter product,
enabling fibre-coupling, is demonstrated.
A laser-written dual-axis optics approach is used to perform challenging slow axis
collimation combined with fast axis correction for closely-packed 49-single-mode
emitter bars, to provide low-loss collimation with high pointing accuracy of less than
3% and 10% of a beam divergence in the fast and slow axis direction, respectively. This
produces excellent source for application beam-combined laser diode systems.
An emitter-by-emitter simultaneous analysis is used to provide spectra and far
field pointing for all emitters and evaluate the performance of various external cavity
configurations with Volume Holographic Gratings (VHGs). For the ultra-collimated
bars, high efficiency VHG-locking is shown to be maintained over enhanced range of
temperatures (>17˚C) and large laser-VHG distances (>110 mm). Highly effective
feedback enables the use of a folded cavity configuration for wavelength selection over
a range of 8 nm for the full 49-emitter bar, giving a prospect for multi-wavelength
single-VHG-locking of bars for cost-effective spectral combining. An innovative
technique of wavelength stepping by individually-formed folded cavities for 5 and 7
sections along the bar demonstrates a potential to produce a source for high
performance dense spectral beam combining.
In a VHG-based Talbot cavity, eight emitters are coherently locked with a highvisibility
interference pattern at 1W of output power. The results of phase-locking for
full 49-emitter bar show that the slow axis pointing variation of ± 2mrad produces
different supermodes, for a fixed alignment of the cavity, thus it must be additionally
corrected for further improvement.||en_US
|dc.publisher||Engineering and Physical Sciences||en_US
|dc.rights||All items in ROS are protected by the Creative Commons copyright license (http://creativecommons.org/licenses/by-nc-nd/2.5/scotland/), with some rights reserved.||
|dc.title||Spatial and spectral brightness improvement of single-mode laser diode arrays||en_US