The prospects of reflectometry and ellipsometry with Colorado State University tabletop XUV laser

The capillary discharge ArIX laser (wavelength 46.9nm) is a new device attractive for various applications due to its unique for XUV lasers properties : high average power and compactness. Reflectometry and ellipsometry are among them. The first is capable to provide fundamental data on optical constants of solids, which are still rather limited. Reflection coefficient in this spectral range is highly sensitive to the presence of an overlayer at the surface of a sample. This hinders bulk optical constants determination, but offers the possibility to study chemical contamination by ambience. The theory of reflection from a surface with a thin overlayer is developed. It enables to rigorously include overlayer into reflectometry data processing and derive separately the parameters of bulk and overlayer. Ellipsometry in general is more powerful than reflectometry method to measure optical constants. In addition it offers the accurate methods to measure film thickness and properties of magnetic materials. Unfortunately high quality analyzers and polarizers are not available in this spectral range, which requires specific approach to ellipsometric measurements. We discuss and use for this purpose Sc/Si multilayer structures

Saturated Table-top Soft X-Ray Lasers by Discharge Excitation

The development of practical "table-top" sources of soft x-ray laser radiation will have a very important impact in many disciplines of science and technology. In the decade that followed the first successful soft x-ray amplification experiments [1,2], large soft x-ray amplification and significant laser output energy could only be obtained using large optical lasers as the energy source. Much progress was accomplished using as pump the same type of lasers utilized in fusion research. However, the widespread use of these sources is limited by their very large size, high cost and low accessibility. These limitations motivates the development of compact soft x-ray laser sources that can impact applications.</jats:p

Progress in the Development of Table-Top Discharge-Pumped Soft X-Ray Lasers

The demonstration of large soft x-ray amplification in a discharge-created plasma has opened a new path to the development of compact and practical soft x-ray lasers. We review our progress in the development and study of these ultrashort wavelength lasers. The field has advanced from the first observation of large amplification in a discharge-created plasma in Ne-like Ar [J.J. Rocca, V.N. Shlyaptsev, F.G. Tomasel, O.D. Cortazar, D. Hartshorn, and J.L.A. Chilla, Phys. Rev. Lett. 73, 2192 (1994)], to the demonstration of an extremely compact saturated laser at 46.9 nm. In this paper we give an overview of these and other selected results. They include the observation of large amplification (gain-length product of 7.5) in Ne-like S at 60.8 nm in material ablated from a solid target by a discharge, and preliminary results of the search for gain at a shorter wavelength in Ne-like Ca. A recent study of the spatial coherence of the capillary discharge 46.9 nm Ne-like Ar laser, which provides the first experimental measurement of a monotonic increase of the spatial coherence with length in a soft x-ray amplifier, is also summarized