in Quantum Electronics
Henry Baltes, Peter Günter, Ursula Keller,
Fritz K. Kneubühl †, Walter Lukosz,
Hans Melchior, Markus W. Sigrist
Cyrill R. E. Bär
New Frontiers in Ultrafast High Power Laser Oscillators.
1st edition 2011. XXVI, 122 pages, € 64,00.
This thesis describes the development of mode-locked laser oscillators that generate high pulse energies and average powers. Such laser sources are particularly interesting for materials processing where they can be used for cutting, drilling or structuring with unprecedented accuracy and speed. From a scientific point of view these high power laser oscillators make experiments such as photoelectron imaging spectroscopy or high harmonic generation accessible at inherently high repetition rates in the megahertz regime. This leads to a better signal-to-noise ratio or a higher photon flux in comparison to the kilohertz laser amplifier systems that are typically employed in this field of application.
All lasers presented here are based on the thin disk technology that provides the required beam quality and power levels. In the framework of this thesis three key parameters of high power mode-locked laser oscillators were pushed to new limits: pulse energy, average power and pulse duration. An Yb:YAG thin disk laser is presented that delivered a pulse energy of 11 μJ at a repetition rate of 4 MHz. Another interesting gain material for high power laser operation is Yb:Lu2O3 as it offers a better thermal conductivity and a broader emission bandwidth than Yb:YAG. Here, the first mode-locked thin disk laser based on Yb: Lu2O3 is presented, followed by subsequent power scaling to an average power of 141 W, which is higher than for previous mode-locked laser oscillators. Moreover, the shortest pulse duration so far achieved from a mode-locked thin disk laser has been obtained from the gain material Yb:LuScO3 that delivered pulses as short as 227 fs.
About the author:
Cyrill R. E. Baer received his Masters degree in Physics in 2006 from the University of Basel, Switzerland. He joined the Institute of Quantum Electronics at ETH Zurich in the same year. His research interests focus on the development of ultrafast laser oscillators with high average powers and pulse energies whose applications are found in materials processing or high field physics experiments. He has written or co-authored more than 50 scientific journal articles and conference contributions.
Keywords: Laser, semiconductor disk laser, ultrafast, mode-locking
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