Thin-disk multipass amplifier for ultrashort laser pulses with kilowatt average output power and mJ pulse energies

Jan-Philipp Negel; Andreas Voss; Marwan Abdou Ahmed; Dominik Bauer; Dirk Sutter; Alexander Killi; Thomas Graf

doi:10.1117/12.2053964

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1 May 2014 Thin-disk multipass amplifier for ultrashort laser pulses with kilowatt average output power and mJ pulse energies

Jan-Philipp Negel, Andreas Voss, Marwan Abdou Ahmed, Dominik Bauer, Dirk Sutter, Alexander Killi, Thomas Graf

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Proceedings Volume 9135, Laser Sources and Applications II; 91351D (2014) https://doi.org/10.1117/12.2053964
Event: SPIE Photonics Europe, 2014, Brussels, Belgium

Abstract

We report on a Yb:YAG thin-disk multipass amplifier for ultrashort laser pulses delivering an average output power of 1.1 kW which to the best of our knowledge is the highest output power reported from such a system so far. A modified commercial TruMicro5050 laser delivers the seed pulses with an average power of 80 W at a wavelength of 1030 nm, a pulse duration of 6.5 ps and a repetition rate of 800 kHz. These pulses are amplified to 1.38 mJ of pulse energy with a duration of 7.3 ps. To achieve this, we developed a scheme in which an array of 40 plane mirrors is used to geometrically fold the seed beam over the pumped thin-disk crystal. Exploiting the incoming linear polarization, an overall number of 40 double-passes through the disk was realized by using the backpath through the amplifier with the orthogonal linear polarization state. Thermal issues on the disk were mitigated by zero-phonon line pumping at a wavelength of 969 nm directly into the upper laser level and by employing a retroreflective mirror pair. The amplifier exhibits an optical efficiency of 44 % and a slope efficiency of 46 %. The beam quality was measured to be better than M²=1.25 at all power levels. As this system can deliver high pulse energies and high average output powers at the same time without the need of a CPA technique, it can be very suitable for high productivity material processing with ultrashort laser pulses.

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Jan-Philipp Negel, Andreas Voss, Marwan Abdou Ahmed, Dominik Bauer, Dirk Sutter, Alexander Killi, and Thomas Graf "Thin-disk multipass amplifier for ultrashort laser pulses with kilowatt average output power and mJ pulse energies", Proc. SPIE 9135, Laser Sources and Applications II, 91351D (1 May 2014); https://doi.org/10.1117/12.2053964

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