7. Vacuum Ultraviolet Lasers

Abstract

The chapter discusses vacuum ultraviolet lasers. Laser plasma ultraviolet (XUV) lasers (XRL) and high-order harmonic generation (HHG) are new sources. For both sources, the short-wavelength limit of the physical process is about a few nanometers, but the intensity and other beam qualities required for most practical uses are achievable only at longer wavelengths. Visible or UV pulsed lasers of large power are an unavoidable part of the technical environment of x-ray lasers and frequency conversion systems as well. The chapter describes the principle of the two sources with examples of contemporary realizations. The chapter presents values of beam intensity, duration, brightness and coherence parameters. X-ray laser applications, which are already in progress, are described in brief. The multiple charged ions of hot plasmas are intense sources of XUV radiation, which is emitted by spontaneous transitions between ion optical levels. High harmonic generation is the nonlinear response of atoms, ions, or even of a steep density-gradient plasma to interaction with an intense electromagnetic field. The chapter also presents a summary on the main properties of vacuum ultraviolet (VUV) beams obtained from high-order harmonic generation.