Generation of 40-ps, terawatt 10-/spl mu/m pulses using self-phase modulation in plasma

Summary form only given. Picosecond/femtosecond pulses can now be amplified to multiterawatt powers at selected wavelengths in the visible and the near-IR spectral regions using the chirped-pulse amplification (CPA) technique. However, amplification of a picosecond pulse with a CO/sub 2/ laser - the only feasible candidate for generation of high-power mid-IR pulses - is difficult because of the relatively narrow bandwidth of the CO/sub 2/ gas and the lack of an adequate CPA technique. The many potential applications, including X-ray generation and laser acceleration of particles, provide a strong motivation for developing a TW CO/sub 2/ laser. We report on amplification of self-chirped 10-/spl mu/m pulses up to a TW level of power, for which a novel pulse shortening technique is used. It is based on the self-phase modulation in a plasma followed by rejection of the chirped part of the pulse in the active medium. We have shown experimentally that, for very-high-power-density pulses, power broadening is a powerful tool to compensate for the lack of bandwidth. Pulses of duration /spl sim/40 ps, much shorter than the pressure broadened bandwidth limit, have been obtained in a CO/sub 2/ amplifier.