Development of Petawatt scale Ti:sapphire laser at 0.05 Hz repetition rate

In our design of Petawatt scale Ti:sapphire laser ("Hercules") a pump laser based on high average power glass (QX-ND, Kigre, Inc) is used at the 100 TW stage. This pump laser generates 14 J of a frequency doubled output at 0.1 Hz repetition rate in 80 ns pulse. In this paper we present a design of a relatively simple and inexpensive extension of this laser allowing to generate pump energy 60-80 J, necessary to reach Petawatt powers. The pump laser consists of a Nd:YLF oscillator, a preamplifier and two 2-pass glass amplifiers with 16-mm diameter phosphate glass rods.