Physics Commons^™

On Imaging Air Pollutants In An Urban Street Canyon Using Tomographic-Doas, Stephen O'Driscoll

Theses

A novel imaging technique based on the combination of differential optical absorption spectroscopy (DOAS) and tomographic reconstruction is presented. This approach, called Tomographic-DOAS, makes it possible to image the spatial distribution of multiple pollutants in an arbitrary region of the atmosphere. Tomographic-DOAS relies on a mathematical model relating measurements of differential optical density to an underlying spatial distribution of pollutants. This model requires the development of an optical system capable of generating multibeam paths or sensing geometries. The optical instrumentation used to construct such sensing geometries is described and a novel scanning beam arrangement that allows a single beam DOAS …

Cold Atom Physics: Trapping Methods And Detection Schemes., Thejesh N. Bandi

Theses

The work presented in this thesis is concerned with the manipulation of laser- cooled rubidium atoms and the detection of small numbers of cold atoms using very sensitive light detectors. Laser-cooled atoms are atoms that have been slowed to very low velocities, corresponding to temperatures of the order of 100 //K, and they can be trapped in magnetic and/or optical traps. The advantage of using cold atoms for experiments in atomic and quantum physics stems from the fact that these atoms are effectively confined within a region of space and this provides longer interaction and observation times compared to atoms …

A Mode-Locked Vertical Extended Cavity Surface Emitting Laser, Aoife Deburca

Theses

Surface emitting lasers are a competitive and flexible alternative to edge emitting lasers. The surface-emitting laser has many useful characteristics, which make it beneficial for many applications. These characteristics include the ease of testing during the growth and the fundamental mode output that is effortlessly achieved

The thesis is focused on the Vertical External Cavity Surface Emitting Laser due to its increased flexibility beyond that of the Vertical Cavity Surface Emitting Laser. A wide range of possible parameters are detailed allowing for flexibility in design and applications.

Optically pumped pulsed cavity configurations were investigated in relation to intra-cavity devices and …