Nonlinear-Optical Method for Combining High Power Laser Beams

摘要

The overall program goal was to investigate concepts for laser-controlled optics based on near-resonance non-linear dispersion in gases, and to demonstrate a laser-induced grating capable of high power laser beam combining. The theoretical work extended the previous year's effort in giving a more detailed view of those aspects which might prevent observation of a grating, and led to optimization of experimental parameters. Modifications and improvements were made to the experimental apparatus. No grating was observed over a wide range of experimental conditions, although the apparatus was capable of such demonstration had a grating existed. The most likely cause of trouble appears to be the complexity of the SF6 medium chosen for demonstration. As a apparatus check, a medium (e.g, vanadium dioxide) can be used in which it is known that a grating can be demonstrated. Measurements were extended on the effect of noble gas admixtures into SF6 on the absorption of 16.26 micrometers radiation; helium suppresses absorption, argon and xenon enhance absorption. It would be worthwhile to continue these studies in light of information to be gained regarding the effect of collisions on absorption spectra in molecular species. (RH)