Picosecond gain dynamics of KrF

We describe the generation of excimer-laser pulses of <10 ps pulse width and up to 40 mJ pulse energy at 248.5 nm and their use in the measurement of ps gain dynamics in a KrF amplifier. Small-signal gain of >2×10⁴, saturation energy density of 2.0 mJ/cm², and gain recovery time of 4 ns were measured. In contrast to XeCl^* no short-gain rcovery time was found in KrF^* and the stored inversion could be fully depleted bya single ps pulse.