Journal Article

PUBDB-2022-02875

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Advantages of YLF host over YAG in power scaling at cryogenic temperatures: direct comparison of Yb-doped systems

Demirbas, U. (Corresponding author)CFEL*DESY* ; Kellert, M.CFEL*DESY* ; Thesinga, J.CFEL*DESY* ; Reuter, S.CFEL*DESY* ; Kärtner, F.CFEL*XFEL.EU*DESY* ; Pergament, M.CFEL*DESY*

2022
OSA Washington, DC

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Please use a persistent id in citations: doi:10.1364/OME.460445  doi:10.3204/PUBDB-2022-02875

Abstract: We have investigated the cryogenic performance of Yb:YAG and Yb:YLF crystals in rod-geometry to understand the pros and cons of each material for the development of ultrafast lasers and amplifier systems. We have performed detailed spectroscopic (absorption, emission, lifetime), temperature, lasing, and thermal-lens measurements with Yb:YLF and Yb:YAG crystals under almost identical conditions. Our analysis has shown that despite the higher thermal conductivity of Yb:YAG, due to its smaller quantum defect, the peak/average temperatures reached under similar pumping conditions is lower in Yb:YLF crystals. Moreover, since the YLF host has a negative thermo-optic coefficient, that balances other positive contributions to thermal lensing, overall Yb:YLF rods possess a much weaker thermal lens than Yb:YAG under similar conditions. As a result of these benefits, we have shown that Yb:YLF rods perform better than Yb:YAG in cryogenic lasing experiments in terms of attainable power performance and laser output beam quality. In terms of gain per pass, the Yb:YAG medium is superior, however, the gain bandwidth is much broader in Yb:YLF systems that make it more suitable for ultrafast pulse laser/amplifier development. We have further shown that, the asymmetric thermal lens behavior of Yb:YLF favors laser operation in E//c axis over E//a axis. The comparison in this study has been performed in rod geometry and for Yb-doping, however, we believe that, to first order, the discussion could be extended to YAG/YLF laser systems doped with other ions (Pr, Nd, Er, Tm, Ho) and to other lasing geometries such as slab and thin-disk.

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Contributing Institute(s):

1. Ultrafast Lasers & X-rays Division (FS-CFEL-2)

Research Program(s):

1. 631 - Matter – Dynamics, Mechanisms and Control (POF4-631) (POF4-631)
2. DFG project 390715994 - EXC 2056: CUI: Advanced Imaging of Matter (390715994) (390715994)
3. AXSIS - Frontiers in Attosecond X-ray Science: Imaging and Spectroscopy (609920) (609920)
4. DFG project 194651731 - EXC 1074: Hamburger Zentrum für ultraschnelle Beobachtung (CUI): Struktur, Dynamik und Kontrolle von Materie auf atomarer Skala (194651731) (194651731)

Experiment(s):

1. AXSIS: Frontiers in Attosecond X-ray Science, Imaging and Spectroscopy
2. Experiments at CFEL

Appears in the scientific report 2022

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