Evolution Of Damage Morphology Research Articles

Research on laser induced damage in PLZT electro-optical transparent ceramic

Nanosecond single and multiple pulses laser damage studies on electro-optic transparent ceramic PLZT ceramic are performed. The evolution of damage morphology and damage probability threshold under multiple irradiations reveals that fatigue effects are affected by both laser fluence and shot numbers. The bulk damage is caused by themal explosion and self-focusing. Femtosecond single and multiple pulses are also employed to irradiate on the sample. Nonlinear absorption property of sample is studied to analyze different damage mechanism. Investigations on laser-induced damage in PLZT are of high practical importance for high-power laser applications.

Laser induced damage in GaAs at 1.06 μm wavelength: surface effects

An experimental study of single shot damage to monocrystal GaAs by a free running laser pulse of 1.06 μm wavelength is described. In order to see the role of surface effects on laser induced damage, samples of different surface finish were prepared. The laser induced damage threshold (LIDT) of lapped GaAs samples is considerably lower than that of the mirror polished samples (ratio 1 2 ). Damage threshold results are analysed in terms of a thermal model incorporating the temperature dependent thermal and optical parameters of GaAs. The combined effect of the enhanced surface absorption and high surface recombination velocity of photo-excited carriers significantly enhances the surface temperature rise and reduces the damage threshold value of GaAs. The evolution of damage morphology is governed by the mechanical damage caused due to the polishing process.

Surface effects on laser-induced damage in Si

The present work describes an experimental study of damage to n-type silicon caused by a normal Nd:glass laser of 1.06 mu m wavelength, running in free-generation mode. Samples of different surface quality were prepared by mechanical lapping, chemical etching and polishing by fine diamond paste. This was done to study the effect of mechanical damage at the sample surface introduced during sample preparation. Damage morphology observed at different power densities shows that in the case of lapped samples the laser damage threshold is considerably lower than that of mirror-polished samples. Damage threshold results are analysed in terms of a thermal model taking into account the differences in the physical parameters of different samples and the temperature dependence of those parameters. The mechanical damage caused at the sample surface during its preparation results in an increase of surface absorptance of Si and consequently lowers its damage threshold. The evolution of damage morphology is governed by the depth of the mechanical damage.