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Optical Engineering

Laser-Induced Damage And The Role Of Self-Focusing
Author(s): M. J. Soileau; William E. Williams; Nastaran Mansour; Eric W. Van Stryland
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Paper Abstract

We review the influence of self-focusing on the measurement of bulk laser-induced-damage (LID) thresholds in normally transparent optical mate-rials. This role is experimentally determined by measuring the spot size and polarization dependence of LID and by observing beam distortion in the far field. Utilizing these techniques, we find that by using a tight focusing geometry in which the breakdown power is below P2, the effects of self-focusing can be practically eliminated in an LID experiment. P2 is the so-called second critical power for self-focusing, and P2 = 3.77P1, where P1 = cX2/327r2n2, where c is the speed of light in vacuum, X is the laser wavelength and n2 is the nonlinear index of refraction. This is in accordance with numerical calculations by J. H. Marburger [in Progress in Quantum Electronics, J. H. Sanders and S. Sten-holm, eds., Vol. 4, Part 1, pp. 35-110, Pergamon, Oxford (1975)]. With this knowledge we determine that damage is only partially explained by avalanche ionization and that the initiation of damage is strongly influenced by extrinsic processes. We therefore conclude that we are measuring extrinsic LID.

Paper Details

Date Published: 1 October 1989
PDF: 12 pages
Opt. Eng. 28(10) 281133 doi: 10.1117/12.7977098
Published in: Optical Engineering Volume 28, Issue 10
Show Author Affiliations
M. J. Soileau, University of Central Florida (United States)
William E. Williams, Litton Laser Systems (United States)
Nastaran Mansour, University of Central Florida (United States)
Eric W. Van Stryland, University of Central Florida (United States)

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