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Title: Rare earth doped silica for integrated optical waveguide lasers and amplifiers
Author: Bebbington, John A.
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1993
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The aim of the project was to realise rare earth doped planar silica waveguide lasers. Research centred on two rare earth ions: neodymium taking advantage of the four level laser system near 1.05 μm and erbium with emission at 1.54 μm, in the important third telecommunication window. Research concentrated on SiO2-P2O5 glass films fabricated by the flame hydrolysis of SiCl4 and PCI3. The resultant low density glass soot was deposited onto silica or oxidised silicon substrates, which was then sintered at temperatures up to 1350°C in a furnace to produce high quality, low loss planar waveguides. The propagation loss of the passive planar films, measured by the three-prism technique, was below 0.1 dB/cm. Rare earth ions were incorporated into the SiC > 2-P205 host glass by the solution doping technique and for the first time in the planar format, by an aerosol doping technique. The propagation loss of the rare earth doped samples was found to be dependent on the rare earth concentration and P2O5 codoping level. Moreover, the loss of the planar films fabricated by the multiple-step solution doping technique was dependent on the fabrication conditions. This problem was circumvented by the aerosol doping technique which incorporated the rare earth ions into the host glass in a single fabrication step and also gave the possibility of regional and vertical selective area doping of planar films. Ridge waveguides were fabricated by a combination of photolithographic and reactive ion etching techniques. Optical assessment of neodymium and erbium doped channel waveguides included fluorescence, absorption and fluorescence lifetime measurements, which supplied information concerning the doping concentrations and ion-ion interactions. Loss measurements were also performed on the channel waveguides with air or Si0 2 -B2 0 3 -P2 0 5 glass acting as the cladding layer. The loss for channel waveguides clad with a glass layer was measured to be below 0.3 dB/cm with a 0.4 wt% rare earth doping level. Finally, oscillation was achieved at 1.054 Jim in 0.4 wt% and 0.5 wt% neodymium doped Si02-P205 channel waveguides. The core dimensions were 6 μm wide, 6 μm thick and 6 cm long. Threshold pump power for continuous wave oscillation was 25 mW for the sample with 0.4 wt% doping level, when pumped at 804 nm. The slope efficiency, with respect to the absorbed pump power, was measured to be approximately 3 % when a 5 % transmitting output coupler was used.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available