Amplification of ultrashort pulses to 0.5 TW at 5 Hz with a flashlamp pumped Cr:LiSAF gain medium

Abstract

We report here the development and construction of a two-flashlamp pumping cavity for a Cr:LiSAF rod, to be operated as a multipass amplifier in a Chirped Pulse Amplifier system. The pumping cavity was designed to minimize the thermal load on the gain medium by the utilization of intracavity filters, aiming operation with high gain and the highest possible repetition rate. Operating as a laser, 30 Hz repetition rate and 20 W average power were obtained for the first time at a maximum gain per pass of 1.5. Changing the pumping characteristics, the laser provided 16 W at 8 Hz repetition rate, at a maximum gain of 3.6. A four-pass multipass amplifier geometry was designed for the pumping cavity, that was integrated and synchronized to a Ti:Sapphire Chirped Pulse Amplifier system. The amplification properties of the gain medium were determined, in one, two and four passes, along with the gain dependence on the repetition rate. The amplifier final configuration provided amplification by a factor 150 to 20 ps stretched pulses, resulting in final compressed pulses with 60 fs and 0.5 TW of peak power at 5 Hz repetition rate.