Characteristics of extreme ultraviolet emission from mid-infrared laser-produced rare-earth Gd plasmas

We characterize extreme ultraviolet (EUV) emission from mid-infrared (mid-IR) laser-produced plasmas (LPPs) of the rare-earth element Gd. The energy conversion efficiency (CE) and the spectral purity in the mid-IR LPPs at lambda(L) = 10.6 mu m were higher than for solid-state LPPs at lambda(L) = 1.06 mu m, because the plasma produced is optically thin due to the lower critical density, resulting in a CE of 0.7%. The peak wavelength remained fixed at 6.76 nm for all laser intensities studied. Plasma parameters at a mid-IR laser intensity of 1.3x10(11) W/cm(2) was also evaluated by use of the hydrodynamic simulation code to produce the EUV emission at 6.76 nm. (C) 2013 Optical Society of America