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Title: A study on the feasibility of a silica-on-silicon blue upconversion laser fabricated by flame hydrolysis deposition
Author: Vermelho, Marcos Vinícius Dias
ISNI:       0000 0001 3546 3740
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1999
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The use of compact blue laser light source is showing a remarkable technological improvement in certain applications, which include devices such as optical data storage, laser printers, and colour displays, to mention a few. Therefore, these applications are requiring more reliable laser sources. Factors such as compactness, robustness, long-term stability, suitability for large-scale integration and possibility of mass-production can be decisive for the choice of the kind of blue laser source as part of a practical tool. Planar lightwave circuits provide practical solutions for such optical devices. A combination of the Flame Hydrolysis Deposition (FHD) and Reactive Ion Etching (RIE) is by now a mature technology, and it has produced planar lightwave circuits for telecommunications applications. In using these analogous technologies, the aim of this work is to study the feasibility of fabrication of compact blue upconversion laser sources. Before proceeding to the study of the blue upconversion process, the research concentrates on the optimisation of the glass host, investigating an alternative approach to reduce the ion-ion interaction in a heavily rare earth doped matrix using sodium ions. The characteristics of the waveguides employed as cavity lasers for the devices fabricated in this planar form also demand accurate numerical modelling for optimisation. Thus, a numerical procedure is developed to complete this general optimisation. The laboratory facilities and availability of experimental data were decisive in the choice of the erbium ion as active material for this first part of the research. The blue upconversion process investigation is initiated by considering two rare earth doping composition for the SiO2-P2O5 glass: a single thulium and a thulium doped sensitised with ytterbium ions. Blue upconversion is examined in both glasses considering future diode lasers pump wavelength. The wavelengths at 800 nm and 980 nm demonstrated to be the potential choices for pumping the Tm/Yb glass. The inclusion of ytterbium ions in the glass composition enhanced the blue upconversion process using the pump wavelength at 800 nm however the population inversion for laser threshold was not predicted by the modelling. The pump wavelength at 980 nm is applied to the numerical model to study the feasibility of the fabrication of this blue upconversion laser. The preliminary results, which do not correspond to the optimised laser structure design, predicted performance comparable to the results of the employment of optical fibre based devices which have been reported so far.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Compact