Accession Number:

ADA094803

Title:

Interaction of Intense Infrared Laser Beams with Transparent Solids.

Descriptive Note:

Final rept. 1 Aug 78-30 Sep 80,

Corporate Author:

WASHINGTON STATE UNIV PULLMAN DEPT OF PHYSICS

Report Date:

1980-12-01

Pagination or Media Count:

77.0

Abstract:

In order to investigate beam deformation and depletion at very high photon fluxes, a computational procedure has been developed that is suitable to simulate the propagation of intense beams through transparent solids. It was applied to NaCl exposed to a FWHM 21 psec pulse from a frequency-doubled 0.532 micron Nd-YAG laser. The energy content of this TEM sub-zero-zero-mode pulse is equal to the experimentally determined single-shot damage threshold of this material. The most convenient mode of data display was found to be a motion picture showing the propagation of the pulse, represented as a colored contour map of the local photon flux, through the focal region. Similar displays of the spatio-temporal development of the free carrier concentration have been made. The material-laser photon interactions in these calculations were based on the two main laser damage mechanisms avalanche ionization and multiphoton-polaron absorption. The most significant result of these investigations is that, according to both models, beam deformation prevents the build-up of a sufficient photon flux in the interaction area to cause damage at this pulse energy. This means that either both damage mechanisms do not explain the best experimentally available data or these data are extrinsic rather than intrinsic features of the material.

Subject Categories:

  • Lasers and Masers

Distribution Statement:

APPROVED FOR PUBLIC RELEASE