SEDL / STP / STP1028-EB / STP18599S

Laser Induced Damage Threshold Derived from Chaotic Electron Dynamics

Becker, W
Astronomy University of New Mexico, Albuquerque, NM

McIver, JK
Astronomy University of New Mexico, Albuquerque, NM

Guenther, AH
Astronomy University of New Mexico, Albuquerque, NM

Pages: 1    Published: Jan 1988

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Abstract

An important stage in the laser induced damage of a dielectric material is a mechanism-initiated triggering by the presence of sufficient electrons in the conduction band. When these electrons are subsequently accelerated by the laser field under photon assistance, they can lead to an electron avalanche, and, in turn, may initiate visible damage.

We have investigated the precondition or presetting of the electron model, i.e. the initial creation of electrons in the conduction band. We assume the presence of small metallic inclusions (r ∼10 to 100 Å) in the dielectric which we model by infinitely deep one-dimensional square well potentials. The dynamics of this model are known to be chaotic if the laser field exceeds a certain threshold value. Under these conditions the electrons can gain enough energy to bridge the gap between the valence band and the conduction band.

The model yields threshold fields of the order of 10¹⁰ W/cm². However, the dependence on the wave length is complicated.