Multiterawatt subpicosecond KrF laser

A 390-fsec pulse with a peak power of 4 TW has been obtained in KrF, yielding an output energy of 1.5 J from an electron-beam-pumped amplifier with an active cross section of 320 cm(2). The amplified spontaneous emission is as low as 1.8% in energy. An initial pulse width of 210 fsec is increased to 390 fsec in the amplifier, mainly as a result of linear dispersion in the thick windows and lenses used throughout the system. Nonlinear absorption and self-phase modulation are not significant in the 2.5-cm-thick CaF(2) output window at an intensity of 13 GW/cm(2).