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Title: Pulsed laser deposition of doped sesquioxide films for planar waveguide lasers
Author: Parsonage, Tina
ISNI:       0000 0004 6348 6490
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2016
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The sesquioxides Y2O3, Lu2O3 and Sc2O3 have been identified as promising laser host materials due to their excellent thermo-mechanical properties and ability to be doped with rare-earth ions. However, crystals of these materials are problematic to grow due to their high melting points of ~2500°C, which means standard methods of crystal growth from a melt need to be modified to deal with such high temperatures and become more expensive. Pulsed laser deposition (PLD) has the capability to grow these materials, without requiring a melt of material to grow from. Sintered ceramic targets of the sesquioxides, often doped with rare-earth ions, are ablated with a UV laser pulse and material is ejected. This plume of material travels through a vacuum chamber to a carefully chosen substrate where material is deposited and forms a crystalline film. Planar waveguide lasers are structures of interest due to their low lasing thresholds in comparison to bulk material, owing to the greater overlap of the pump and laser modes, and their large aspect ratio that allows efficient heat removal from the laser crystal. This, combined with the high thermal conductivity of the sesquioxides, should allow for power scaling of these waveguide lasers with minimal thermal affects. The laser results in this thesis are for progressively higher powers, and no detrimental heating affects are witnessed. This thesis reports on the growth of single and multilayer sesquioxide waveguides grown by PLD, including growth optimisation, sample analysis and laser experiments. The first sample of this project to be successfully lased was a single layer Tm:Y2O3 waveguide on a YAG substrate, which produced a maximum output power of 35 mW with 9% slope efficiency at a wavelength of 1.95 µm, and, to the best of our knowledge, was the first Tm:Y2O3 planar waveguide laser. Next, Yb:Y2O3 was the material of choice and a multilayer sample was fabricated, where the Yb:Y2O3 core was sandwiched between two undoped Y2O3 layers, again on a YAG substrate. Laser experiments with this waveguide gave a maximum output power of 1.2 W at 1030 nm, with a slope efficiency of 20%. The highest laser output power of any of the doped sesquioxide waveguides in this project is 8.5 W, achieved using a Yb:Lu2O3 sample.
Supervisor: Eason, Robert Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available