This thesis deals with the subject of fibre optic magnetic field sensors utilizing iron garnet materials. Such materials exhibit a large Faraday rotation which make them advantageous for application in compact mag­netic field sensors. After an introduction, in which fibre optic sensors and optical methods to measure electric current are reviewed, the original research work is summarized. A system for the measurement of the magneto-optic properties of trans­parent materials is described. Measurement results, showing the influence of temperature, magnetic field direction and sample treatment on the magneto-optical proper­ties of YIG-crystals, are presented. The proper­ties of thin magneto-optical waveguiding films have also been studied using different light coupling methods. Measurement results obtained for holo­graphic grating, prism and edge (end-fire) light coupling to different substituted YIG films are presented. It is shown that the launching method may affect the properties to be measured. The design and performance of several versions of extrinsic guided wave fibre optic magnetic field sensors are then reported. The sensors employ substi­tuted YIG (Yttrium Iron Garnet, Y3Fe5O12) thin film waveguides as sensing elements. Polari­zation maintaining fibres were used as feed and return to provide two signal channels. The signals were combined in a balanced measure­ment system, providing insensitivity to both fluctuations in optical power and loss. Sensors have been made both with separate fibres to guide the light to and from the sensing element and with a single fibre for both functions. The two fibre version, although less ”elegant”, is found to have a better performance. This version also makes it possible to determine both the magnitude and sign of the magnetic field. Measurement results indicate a usable measurement range of at least several mT with a noise equivalent magnetic field level of less than 8 nT/root(Hz). The design and performance of multimode fibre optic magnetic field sensors utilizing the Faraday effect in an epitaxially grown thick (YbTbBi)IG film is also described. This type of sensor is found to be linear over a range from 27 mT to less than 270 nT. Sensor prototypes suitable for current monitoring in high voltage transmission lines have also been developed. / QC 20111209 / YIG

<p>The enhancement of the emission from nitrogen vacancy color centers will help facilitate advancements in quantum information technology. To this end, the reduction of the excited state lifetimes of NVs as well as the design of devices which support electroluminescence of nitrogen vacancies, as well as the broadband enhancement of the emission from these centers is of great importance.</p> <p> </p> <p>In this study, we create diamond thin films containing nitrogen vacancy color centers using salt-assisted ultrasonic disaggregation techniques and electrophoretic deposition. These films are implanted with xenon atoms and the resulting structures are characterized optically. We report a reduction in the bulk emission lifetime of nitrogen vacancy color centers of two orders of magnitude. A coupled-mode theory approach is used to analyze the emission from the xenon-doped nanodiamond species. It is determined that the lifetime reduction occurs due to coupling between nitrogen vacancy color centers and xenon color centers within the diamond lattice.</p> <p> </p> <p>A diamond field effect transistor is investigated via simulations utilizing Sentaurus TCAD software. The device is scaled by three orders of magnitude from previous experiments involving the same structure. Transport characteristics are obtained from simulation results. We confirm the existence of a decreasing saturation voltage with a decrease in gate length in the diamond field effect transistor. Further investigation into the device’s viability as a quantum emitter is conducted. </p> <p> </p> <p>The design of a single photon source utilizing plasmonic structures to enhance emission from nitrogen vacancy color centers is proposed. The plasmonic structure is investigated to extract operating parameters and to quantify the optical coupling and propagation characteristics for various physical dimensions</p> <p> </p> The design of a plasmonic device which features both electroluminescence via nitrogen vacancy color centers and their enhancement via plasmonic effects is numerically simulated. The device features large Purcell enhancement factor and good photon emission rate. In summary, this work paves the way towards the advancement of the nitrogen vacancy color center as a stable source of room temperature photons for quantum information applications.

<p>Dipole-dipole interactions are ubiquitous fundamental physical phenomena that govern physical effects such as Casimir Forces, van der Waals forces, collective Lamb shifts, cooperative decay, and resonance energy transfer. These interactions are associated with real and virtual photon exchange between the interacting emitters. Such interactions are crucial in realizing quantum memories, novel super-radiant light sources, and light-harvesting devices. Owing to this, the control and modification of dipole-dipole interactions have been a longstanding theme. The electromagnetic environment plays a crucial role in enhancing the range and strength of the interactions. This work focuses on modifying the nanophotonic environment near interacting emitters to enhance dipole-dipole interactions instead of spontaneous emission. To this end, we focus on engineering the nanophotonic environment to enhance the strength and range of dipole-dipole interactions between an ensemble of emitters. We explore ordered and disordered nanophotonic structures. We experimentally demonstrate long-range dipole-dipole interactions mediated by surface lattice resonances in a periodic plasmonic nanoparticle lattice. Further, the modified electromagnetic environment reduces the apparent dimensionality of the interacting system compared to non-resonant in-homogeneous and homogeneous environments. We also develop a spectral domain inverse design technique for the accelerated discovery of disordered metamaterials with unique spectral features. </p> <p>Further, we explore the novel regimes of light localization at near-zero-index in such disordered media. The disordered near-zero-index medium reveals enhanced localization and near-field chirality. This work paves the way to engineer the electromagnetic nanophotonic environment to realize enhanced long-range dipole-dipole interactions.</p>