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Title: Development of versatile high power bounce geometry lasers
Author: Chard, Simon Peter
ISNI:       0000 0004 2695 1867
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2011
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This thesis details an investigation into the development of bounce geometry lasers to achieve a more versatile range of laser characteristics. The bounce geometry has matured in recent years into a useful solid-state pumping scheme, but its performance has to date been limited by a number of factors, as well as largely restricted to neodymium systems. For real-world application, a more versatile range of laser characteristics would be desirable. A new design for a bounce geometry amplifier is presented that achieves a symmetric gain profile and thermal lens by control of the amplifier dimensions. The laser produces a circular stigmatic TEM00 (M2 < 1:11) beam with 14 W power. When Q-switched, the design permits versatile control over the repetition rate (single-shot to 480 kHz) with pulse energies up to 0.45 mJ. The stigmatic design also allows the direct generation of a Laguerre-Gaussian `vortex' beam, and proves favourable for modelocking with the nonlinear mirror method. Several designs are investigated to study power scaling in a master oscillator power amplifier (MOPA) configuration, including a stigmatic MOPA based on the amplifier described above, and a chain of multiple power amplifiers. A folded dual-pumped amplifier design is also demonstrated, which reduces the size and complexity of a multi-stage amplifier and allows power scaling to the 100 W level. Pulse amplification is also investigated, and a MOPA is optimised for energy extraction by a Q-switched oscillator. Finally a 3-micron bounce laser is presented using an erbium-doped YSGG gain medium. Different cavity designs are investigated, and a simple compact cavity is found to be optimum. Thermal effects are investigated and found to be a limiting factor on the laser's performance. Quasi-continuous wave pulse energies of up to 15 mJ are demonstrated, with an average power of up to 430 mW.
Supervisor: Damzen, Michael Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral