Abstract

It has recently been shown that the well-defined geometry of a gaseous beam, the cooling that results from a supersonic expansion, and the relative simplicity of a pulsed nozzle make a pulsed supersonic beam source most desirable in providing a simple scheme for gas-phase third harmonic generation of radiation to the extreme ultraviolet. A simple model has since been developed to describe the third harmonic generation process in a pulsed beam. The model employs three basic assumptions: first, that the gas density in the jet has a rectangular profile in the direction of propagation of the laser beam; second, that the length of the profile is determined by the conservation of particle flux through all planes perpendicular to the forward direction of the jet; and third, that the laser field is propagating in the plane-wave regime. Using this model, predictions on the functional dependence of the output on reservoir gas density, nozzle diameter, nozzle distance from the laser focus, and other gaseous medium parameters are obtained and are compared, with results from experiments on frequency tripling to 118.2 nm in a xenon jet. Good agreement is obtained.

© 1984 Optical Society of America