PICOSECOND PUMPING OF EXTREME-ULTRAVIOLET LASERS USING PREFORMED LASER PLASMAS

Weak laser prepulses were used for the first time with picosecond-dura tion laser light to enhance laser-target absorption for efficient exci tation of extreme-ultraviolet lasers. A traveling-wave excitation geom etry and a self-healing mercury-wetted target were used with 300-ps pr epulses to pump the photoionization Xe III laser at 109-nm wavelength. Fully saturated laser gain was demonstrated for both 32-ps and 1.4-ps pump pulses with use of only 150-mJ pulse energy: small-signal gain c oefficients exceeded 2 cm(-1) for on-target laser fluences of only 4 J /cm(2). (C) 1996 Optical Society of America