Abstract

High-order-harmonic generation in noble gas ions by focused laser pulses provides a potentially useful source of high-spectral- brightness, coherent, VUV emission. When a spatially Gaussian laser pulse is focused in the atomic medium, the harmonics are emitted collinearly with the laser and are centrally peaked, or at least uniform, around the laser axis.¹-² The presence of the intense laser accompanying the harmonic pulse limits the proximity of any material to the focus and requires a mechanism for separating the harmonic and laser beams. When using a grating spectrometer, the grating must be far enough away, and hence large enough, to avoid damage by the laser pulse. This places severe experimental constraints.

© 1994 Optical Society of America