Advantages of YLF host over YAG in power scaling at cryogenic temperatures: direct comparison of Yb-doped systems

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