Efficient shortening of self-chirped picosecond pulses in a high-power CO2amplifier

We report a factor-of-6 shortening of the 240-ps (FWHM) pulses in a triple- pass, 2.5-atm CO2 amplifier. This technique is based on the self-phase modu lation 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 a mplify 40-ps pulses to terawatt power levels. (C) 2001 Optical Society of A merica.