Abstract

Diode pumped Yb-doped based ultrafast laser systems are of great interest either as direct high intensity systems or as pump sources for OPCPA based systems operating in the extremely short pulse duration regime. Yb-doped tungstates such as Yb:KYW are well known both for their high gain and broad bandwidth and seem to be the right material choice towards a medium energy level amplification of broad bandwidth pulses [1]. However, due to their relatively limited energy storage capacity, with an upper state lifetime of 300 μs, they have been so far restricted to relatively low energy applications at high repetition rates. Yb:CaF₂ on the other hand is a very promising material mainly because of its broad gain bandwidth and high energy storage capacity [2, 3]. The main limitation in this case is the very high saturation fluence of Yb:CaF₂, resulting in low gain amplifiers or reduced energy extraction efficiencies. In this paper, we present a diode-pumped multipass amplifier based on Yb:CaF₂ using passive coherent combining in order to access the 100 mJ range without optical damage.

© 2013 IEEE