Cryogenic Lasers
Cooling of the gain medium in a laser to cryogenic temperatures, ca. 80 K, can enable lasing at higher powers with improved beam quality. This improvement is due to a significant decrease in thermo-optical and thermo-mechanical distortions within crystalline gain media, resulting from an increase in thermal conductivity, a reduction in thermal expansion and a reduction in the temperature dependence of the refractive index. Additionally, for quasi-three-level gain media, the collapse of the thermal Boltzmann distribution in the lower manifold significantly improves the efficiency of the laser. However, the differential thermal contraction within the laser head as it is cooled from room temperature can lead to wavefront distortion and birefringence that eliminates the advantages of cooling.
We have developed a compact and efficient cryogenic Yb:YAG laser that fully exploits the advantages of cryogenic cooling and can be scaled to high power with diffraction-limited beam quality. The laser uses a conduction cooled, end pumped, zigzag slab geometry. We have demonstrated 208 W in a TEM00 beam with a slope efficiency of 64%. There was no measurable degradation in the gain medium or slope efficiency.
Publications
- A cryogenic, end pumped, zigzag slab laser suitable for power scaling
Miftar Ganija, David Ottaway, Peter Veitch and Jesper Munch
IQEC/CLEO Pacific Rim 2011 (Australian Optical Society, 2011) p.627 - Cryogenic, conduction cooled, end pumped, zigzag slab laser suitable for power scaling
Miftar Ganija, David Ottaway, Peter Veitch and Jesper Munch
CLEO Technical Digest (Optical Society of America, 2012) paper CM3D.7 - Cryogenic, high power, diffraction limited, Yb:YAG slab laser
Miftar Ganija, David Ottaway, Peter Veitch and Jesper Munch,
Optics Express, 21, 6973 (2013)
Personnel
Sophie Hollitt
Miftar Ganija
Dr David Ottaway
Prof Jesper Munch
A/Prof. Peter Veitch
