Laser-induced damage of optical thin films submitted to 343, 515, and 1030 nm multiple subpicosecond pulses

Abstract

Laser-induced damage of optical thin films submitted to 343, 515, and 1030 nm multiple subpicosecond pulses Dam-Bé Douti Laurent Gallais Mireille Commandré Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 05/15/2015 Terms of Use: http://spiedl.org/termsLaser-induced damage of optical thin films submitted to 343, 515, and 1030 nm multiple subpicosecond pulses Abstract. Optical materials submitted to multiple subpicosecond irradiations are known to exhibit a decrease of the laser-induced damage threshold (LIDT) with the applied number of pulses, an effect referred to as "fatigue" or "incubation." In this work, we experimentally investigate this effect for the case of optical thin films submitted to multiple exposures with 500 fs pulses at different wavelengths: 1030, 515, and 343 nm. Niobia, hafnia, and silica films made with dense coating techniques (magnetron sputtering, ion-assisted deposition, and reactive low voltage ion plating) are studied, as well as the surface of a fused silica substrate. These samples have been exposed to different pulse numbers (from 1 to 100,000) at a low-frequency repetition rate (less than 1 kHz) and the LIDT has been measured. The results reveal the differences between materials and for the various wavelengths such as the decrease rate of the LIDT or the stabilization level that is reached after multiple exposures. All the results evidence the role of native-and laser-induced defects that we discuss on the basis of published works on the subject. Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 05/15/2015 Terms of Use: http://spiedl.org/terms

Laser damage growth with picosecond pulses

“…Overall, it has been demonstrated that the laser damage resistance of an optic in the subpicosecond regime is both limited by its intrinsic properties (linked to its electronic structure) [7,8] and by the presence of embedded defects induced by the manufacturing process [4,9]. The densities of such embedded defects can be as high as two hundreds of defects∕cm 2 , estimated from the measurement of damage densities during rasterscan tests [10]. The questions we wanted to answer in this Letter are: Once a damage site is initiated, what is its growth probability?…”

“…In this context, many studies have been carried out to better understand laser damage resistance of optical components. In the case of subpicosecond laser systems, the effect of irradiation conditions (fluence, pulse duration, wavelength, number of pulses, and environment) [1][2][3][4], design and manufacturing conditions (coating process, materials, electric-field distribution) [5,6] were thoroughly studied. Overall, it has been demonstrated that the laser damage resistance of an optic in the subpicosecond regime is both limited by its intrinsic properties (linked to its electronic structure) [7,8] and by the presence of embedded defects induced by the manufacturing process [4,9].…”

Analysis of energy deposition and damage mechanisms in single layer optical thin films irradiated by IR and UV femtosecond pulses

“…This ratio is calculated numerically based on the refractive index and film thickness deduced from spectrophotometric measurements. Band gap (eV) Band gap (eV) 8 …”

Thin films characterizations to design high-reflective coatings for ultrafast high power laser systems

“…We observe a decrease of the LIDT with the number of applied pulses that corresponds to a drop of more than 20% of the threshold in the first 100 pulses, as observed in other works with similar irradiation conditions. 12,13 This behavior was attributed to the high densities of deep and shallow traps, i.e. electronic states in the forbidden band that can trap the conduction band electrons after a subthreshold irradiation.…”