Statistical study of single and multiple pulse laser-induced damage in glasses

Abstract

Single and multiple pulse laser damage studies are performed in Suprasil silica and BK-7 borosilicate glasses. Experiments are made in the bulk of materials at 1.064microm with nanosecond pulses, using an accurate and reliable measurement system. By means of a statistical study on laser damage probabilities, we demonstrate that the same nano-precursors could be involved in the multiple shot and single shot damage process. A damage mechanism with two stages is then proposed to explain the results. Firstly, a pre-damage process, corresponding to material changes at a microscopic level, leads the precursor to a state that can induce a one-pulse damage. And secondly a final damage occurs, with a mechanism identical to the single shot case. For each material, a law is found to predict the precursor life-time. We can then deduce the long term life of optical elements in high-power laser systems submitted to multipulse irradiation.

Effect of subsurface impurities of fused silica on laser-induced damage probability

“…The experimental setup for laser-damage test has been described in detail elsewhere, 11,17 and only a brief description is given here. The data points of laser damage probability are measured at 355 nm using injected Nd:YAG laser with the Gaussian temporal profile.…”

“…The information on damage density and damage threshold of precursors can be extracted from the experimental curves of damage probability. 11,17 Feit and Rubenchik have presented a model 18 that the size distribution of nanoabsorbers is related to the damage density and damage probability, which predicts the dependence of damage density on pulse duration.…”

Transportation of megawatt millijoule laser pulses via optical fibers?

“…The measured damage threshold was around 4.4 GW/cm 2 , which is in agreement with that reported in the literature. An appropriate method for determining the LIDT can be found in recent publications [31,32]. For fused silica, which is one of the most common material for fibers, the LIDT behaves according (τ P ) 1/2 and is around 5 GW/cm 2 for ns-pulses [27].…”

Laser-PMMA Interaction and Mechanical Stresses

“…Particular procedures are used to determine the damage threshold, which depends on the administrative regulations, on the purpose of the component application (medical, industrial) and is specific for each country [6][7][8][9][10].…”

“…Polystyrene and PMMA have similar behavior during the laser beam interaction. Of special interest is to observe the statistics of cracks formation [7,9]. It is common [7] to investigate the interaction with: low power (1-10 MW) and long focal length (50-100 mm); high power (50-100 MW) and long focal length (50-100 mm); high power and short focal length (< 50 mm).…”