Development of a High Repetition Rate, Electro-optically Q-switched Ho:YAG Laser

Lasers operating within the 2 μm region of electromagnetic spectrum find use across a wide range of fields and applications. These include medical, material processing, LiDAR, and as pump sources for the generation of mid-infrared light. For these reasons, the aim of this research was to develop a high repetition rate, electro-optically Q-switched Ho:YAG laser capable of meeting the requirements for these applications, and as a result, investigate if it is theoretically capable of pumping an optical parametric oscillator. The basis of the research was built upon the development of a continuous-wave free-space Ho:YAG oscillator utilising a near-concentric cavity. This laser produced two emission lines at 2090 and 2097 nm, with a beam quality of M2 < 1.13. The output powers of the laser were capable of scaling up to 40 W at a slope efficiency of 62.1%, without any evidence of roll off. This laser was then adapted to be electro-optically Q-switched via the addition of an RTP Pockels cell, a quarter-waveplate, and a Brewster’s angled ZnSe window. The system was able to operate over a range of repetition rates between 8 and 11 kHz, and up to an average output power of 12.75 W at a slope efficiency of ~42.5%. The inclusion of the Q-switching intra-cavity elements caused the emission spectrum to shift to a single line at 2122 nm. The laser’s output scaled up to pulse energies of 1.59 mJ and durations of 40.5 ns, which enabled peak powers on the order of 37 kW. Finally, a range of modelling was undertaken in regard to a ZGP based doubly resonant optical parametric oscillator. This modelling indicated that the operational threshold of a theoretical OPO is able to be met by the output powers of the Q-switched 2.1 μm laser, without exceeding the damage threshold of the system.

Author dc:creator

• Rogers, Henry Duncan

Advisors dc:contributor.advisor

• Ganija, Miftar
• Boyd, Keiron

• Lasers
• Optics
• Ho:YAG
• Electro-optics
• Q-switch

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/2440/145195

OAI identifier oai:identifier

oai:digital.library.adelaide.edu.au:2440/145195