Suppression of the pedestal in a chirped-pulse-amplification laser

Abstract

The pedestal (prepulse and postpulse) associated with a chirped-pulse-amplification (CPA) laser is studied. Four components have been identified that contribute to the pedestal. Pulses are spectrally shaped by gain narrowing in a frequency-matched, regenerative amplifier, while self-phase modulation is avoided. The intensity contrast is further improved through the use of a saturable absorber, resulting in Gaussian pulses of ~0.9-ps duration with an intensity contrast exceeding 105:1. Both experimental and numerical descriptions of these processes are presented. This investigation makes possible the study of high-intensity ultrashort laser–plasma interactions with a fiber–grating CPA system.