Generation of 21-fs millijoule-energy pulses by use of Ti:sapphire

We have demonstrated the generation of 21 ± 2 fs duration pulses, with an energy of 0.5 mJ, a bandwidth of 44 nm, and a repetition rate of 10 Hz, using a chirped-pulse amplification scheme in Ti:sapphire. We use 11-fs, 5-nJ pulses from a Ti:sapphire oscillator as the input for an eight-pass Ti:sapphire amplifier. A broadband, low-dispersion chirped-pulse stretcher-and-amplifier design was used for propagation and amplification of the ultrashort pulses. By the addition of a prism pair to the stretcher, both the second- and third-order dispersions are minimized, permitting us to generate near-transform-limited amplified pulses at a duration near the theoretical limit imposed by gain narrowing in Ti:sapphire.