Generation of 35.5-nm coherent radiation

Third-harmonic generation in positively dispersive gases with a novel cell

The generation of UV third-harmonic radiation by a focused laser beam in a positively dispersive gaseous medium is investigated. The nonlinear gas is confined to a focal half-space by using a differentially pumped gas cell. The resulting density gradient along the beam axis is shown to provide an efficient frequency conversion in spectral regions of positive dispersion. Experimental results obtained in argon at λ ~ 197 nm, which compare favorably with theory, are presented.

Two-photon resonances in Xe and Kr for the generation of tunable coherent extreme UV radiation

Using eleven two-photon resonances in Xe and Kr, a comparative study of the resonant third harmonic generation and saturation properties in the 70.9-75.5-nm extreme ultraviolet (XUV) region was made. The fundamental deep ultraviolet radiation was produced in a nonlinear crystal beta-BaB(2)O(4). The two-photon resonances 5p-6p'[1/2](0) and 8p[1/2](0) in Xe, as well as the 4p-5p[1/2](0) and [5/2](2) resonances in Kr, are useful for efficient tunable XUV generation in the 71-92-nm region.

Tunable extreme-ultraviolet radiation from 105 to 87.5 nm using Hg vapor

Tunable, coherent radiation has been generated in the region 105 to 87.5 nm by resonant four-wave frequency mixing in Hg vapor. A glass capillary array forms an efficient XUV window with 50% transmission. An absorption spectrum of N(2) was recorded at 89 nm with a resolving power of 2 x 10(5).

Tunable Coherent X-rays

A modern 1- to 2-billion-electron-volt synchrotron radiation facility (based on high-brightness electron beams and magnetic undulators) would generate coherent (laser-like) soft x-rays of wavelengths as short as 10 angstroms. The radiation would also be broadly tunable and subject to full polarization control. Radiation with these properties could be used for phase- and element-sensitive microprobing of biological assemblies and material interfaces as well as reserch on the production of electronic microstructures with features smaller than 1000 angstroms. These short wavelength capabilities, which extend to the K-absorption edges of carbon, nitrogen, and oxygen, are neither available nor projected for laboratory XUV lasers. Higher energy storage rings (5 to 6 billion electron volts) would generate significantly less coherent radiation and would be further compromised by additional x-ray thermal loading of optical components.