A Study on the Feasibility of a Silica-on-Silicon Blue Upconversion Laser Fabricated by Flame Hydrolysis Deposition

Vermelho, Marcos Vinicius Dias (1999) A Study on the Feasibility of a Silica-on-Silicon Blue Upconversion Laser Fabricated by Flame Hydrolysis Deposition. PhD thesis, University of Glasgow.

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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.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: J S Aitchison
Keywords: Electrical engineering
Date of Award: 1999
Depositing User: Enlighten Team
Unique ID: glathesis:1999-76204
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 Nov 2019 16:28
Last Modified: 19 Nov 2019 16:28
URI: https://theses.gla.ac.uk/id/eprint/76204

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