Abstract

We review the evolution of chirped pulse amplification into the 10-fs regime. This evolution has been made possible by the advent of ultrabroadband amplification media such as Ti:sapphire, the development of sub-10-fs laser Kerr-lens-modelocked oscillators [1, 2] to provide stable and reliable seed pulses for amplification and the implementation of new technologies and strategies to minimize or circumvent gain narrowing and higher order phase distortions during amplification. As an example, a three stage, multi-output, laser system, at the University of California at San Diego will be described. This system is designed to produce > 1-J pulses of ~15-fs duration at a 10-Hz repetition. After two stages of amplification, 18-fs, 4-TW pulses have been produced at a repetition rate of 50 Hz and an average power > 4 W.[3] To our knowledge, these are the shortest duration terawatt pulses yet produced by a chirped pulse amplification system. Pulses at this level have been used at UCSD to produce ultrafast x-rays (both broadband and K_α radiation) for use in ultrafast diffraction studies of molecular dissociation, ultrafast near edge absorption studies of molecular dynamics, and time-gated x-ray mammography and angiography. Full system amplification at a 10 Hz repetition rate to energies of approximately 2 J before compression has also been demonstrated and transform limited pulses of ~20 fs have been measured. These pulses will be used for investigations of high field phenomena in the highly relativistic regime (i.e. at intensities > 10²⁰ W/cm²), charged particle acceleration relevant to laser driven nuclear fusion and hard x-ray lasers. Further optimization of both intermediate and full level amplified outputs which to date have been limited to amplified bandwidths of ~ 70 nm is currently underway and should result in compressed pulse durations of < 15-fs and peak powers of > 70 TW.

© 1997 Optical Society of America