Efficient shortening of self-chirped picosecond pulses in a high-power CO_2 amplifier

Abstract

We report a factor-of-6 shortening of the 240-ps (FWHM) pulses in a triple-pass, 2.5-atm CO(2) amplifier. This technique is based on the self-phase modulation of a 10-mum pulse in a plasma after the first pass of amplification, followed by narrowing of this chirped pulse during further amplification. Subsequently, strong power broadening provides the necessary bandwidth to amplify 40-ps pulses to terawatt power levels.