Physics Commons^™

G-Factors For Ternary Crystals Of Groups Iii And V, Liviu Mateescu

Theses

The objective of this thesis is to present a method of calculating the g-factors of ternary crystals of III-V group elements.

There is an increasing interest in knowing the magnetic behavior of different semiconductor materials, due to advances in the domain of spintronics. The g-factors were calculated for the conduction electrons, since they have the greatest contribution to the magnetic properties of the crystal. The thesis presented here proposes a method to calculate the magnetic g-factor of whole families of crystals made of three elements, of the form A_1-xB_xC, for eleven values, x ε {0, 0.1, …

Energy Aware Communications Framework For Ieee 802.15.4 Wireless Sensor Networks, Rodolfo De Paz Alberola

Theses

A wireless sensor network (WSN) is a network of sensor nodes that functions in a cooperative manner to monitor the changes in the physical environment. Typically, sensor nodes are deployed in places with difficult access, if any, to an external power supply thus requiring battery power. Therefore, WSN communication protocols must be designed with energy efficient and self-organizing capabilities in mind. In this context, the IEEE 802.15.4 standard is being widely employed for the lower layers of low-cost, low-rate and low-power wireless sensor communications due to its potential to fulfil requirements of various monitoring and control applications. However, the specification …

Optically Injected And Mutually Coupled Frequency Distinct Semiconductor Lasers, Beatriz Baselga-Pascual

Theses

In the following work we examine the dynamics of semiconductor lasers under different types of coupled oscillator configurations, namely optical injection and mutual coupling. We examine both discrete-mode quantum well lasers and distribute feedback quantum dot lasers. First we describe optical injection experiments carried out on single mode semiconductor lasers. Conventional diagnostic tools such as optical spectra, RF spectra and intensity time series are used to describe the dynamics. We also describe a novel interferometric technique used to experimentally resolve the phase of the slave laser. This new technique has proved successful, revealing some heretofore hidden dynamical features and showing …

Quantum Engineering Of Laser-Cooled Atoms: Experiments And Theory, Kieran Deasy

Theses

In this thesis, laser cooling and trapping techniques are implemented to forrn a cold atom cloud of 85Rb atoms in a magneto-optical trap (Mon configuration. The system produces an atom cloud of~ 1.5 mm in diameter, containing ~ 108 atoms and an average temperature in the sub-Doppler range. Tapered optical fibres (TOFs) are also detailed here, including their guiding properties and the process used for their fabrication. Many possible applications for TOFs have been proposed and one such application is investigated, i.e. the use of TOFs as highly sensitive atom probes. The research results contained within this thesis describe two …