Picosecond pumping of extreme-ultraviolet lasers using preformed laser plasmas

Abstract

Weak laser prepulses were used for the first time with picosecond-duration laser light to enhance laser-target absorption for efficient excitation of extreme-ultraviolet lasers. A traveling-wave excitation geometry and a self-healing mercury-wetted target were used with 300-ps prepulses 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 coefficients exceeded 2 cm−1 for on-target laser fluences of only 4 J/cm2.