Yb:tungstate waveguide lasers
MetadataShow full item record
Lasers find a wide range of applications in many areas including photo-biology, photo-chemistry, materials processing, imaging and telecommunications. However, the practical use of such sources is often limited by the bulky nature of existing systems. By fabricating channel waveguides in solid-state laser-gain materials more compact laser systems can be designed and fabricated, providing user-friendly sources. Other advantages inherent in the use of waveguide gain media include the maintenance of high intensities over extended interaction lengths, reducing laser thresholds. This thesis presents the development of Yb:tungstate lasers operating around 1μm in waveguide geometries. An Yb:KY(WO₄)₂ planar waveguide laser grown by liquid phase epitaxy is demonstrated with output powers up to 190 mW and 76 % slope efficiency. This is similar to the performance from bulk lasers but in a very compact design. Excellent thresholds of only 40 mW absorbed pump power are realised. The propagation loss is found to be less than 0.1 dBcm⁻¹ and Q-switched operation is also demonstrated. Channel waveguides are fabricated in Yb:KGd(WO₄)₂ and Yb:KY(WO₄)₂ using ultrafast laser inscription. Several of these waveguides lase in compact monolithic cavities. A maximum output power of 18.6 mW is observed, with a propagation loss of ~2 dBcm⁻¹. By using a variety of writing conditions the optimum writing pulse energy is identified. Micro-spectroscopy experiments are performed to enable a fuller understanding of the induced crystal modification. Observations include frequency shifts of Raman lines which are attributed to densification of WO₂W bonds in the crystal. Yb:tungstate lasers can generate ultrashort pulses and some preliminary work is done to investigate the use of quantum dot devices as saturable absorbers. These are shown to have reduced saturation fluence compared to quantum well devices, making them particularly suitable for future integration with Yb:tungstate waveguides for the creation of ultrafast, compact and high repetition rate lasers.
Thesis, PhD Doctor of Philosophy
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.
Showing items related by title, author, creator and subject.
Clinical effectiveness and cost-effectiveness of foam sclerotherapy, endovenous laser ablation and surgery for varicose veins : results from the comparison of LAser, Surgery and foam Sclerotherapy (CLASS) randomised controlled trial Brittenden, J.; Cotton, S.C.; Elders, A.; Tassie, E.; Scotland, G.; Ramsay, C.R.; Norrie, J.; Burr, J.; Francis, J.; Wileman, S.; Campbell, B.; Bachoo, P.; Chetter, I.; Gough, M.; Earnshaw, J.; Lees, T.; Scott, J.; Baker, S.A.; MacLennan, G.; Prior, M.; Bolsover, D.; Campbell, M.K. (2015-04) - Journal articlePrimary outcome measures: Disease-specific [Aberdeen Varicose Vein Questionnaire (AVVQ)] and generic [European Quality of Life-5 Dimensions (EQ-5D), Short Form questionnaire-36 items (SF-36) physical and mental component ...
Sarmani, Abdul Rahman (University of St Andrews, 2008) - ThesisUltralow threshold, compact and highly efficient femtosecond lasers based on Yb³⁺-doped potassium yttrium tungstate (Yb:KYW) and Yb³⁺-doped vanadium yttrium oxide (Yb:YVO 4 ) have been demonstrated within this PhD-research ...
Tsiminis, Georgios (University of St Andrews, 2010) - ThesisThis thesis describes a number of studies on organic semiconductors focused around using them as gain media for lasers. The photophysical properties of organic semiconductors are studied using a wide range of ...