Characterization of extreme ultraviolet emission using the fourth harmonic of a Nd:YAG laser

Abstract

Characterization of an extreme ultraviolet (EUV) emission from laser-produced tin plasma was investigated for 266 and 1064nm laser wavelengths. The EUV emission exhibits a laser-wavelength dependence in terms of angular distribution and structures of emission spectra. Angular distributions expressed in a form of I(θ)∝cosαθ became α=1.3 and 0.5, respectively, for 266 and 1064nm laser wavelength. It is found that spectra from 266nm laser plasma show dips at around 13.5nm that had been well replicated in computer simulations. Both angular distribution and spectral structure at 13.5nm suggest the existence of an opaque plasma region in front of the EUV source plasma generated by 266nm radiation.