Influence of process conditions on the optical properties HfO 2 /SiO 2 thin films for high power laser coatings

Langdon, B.; Patel, D.; Krous, E.; Rocca, J. J.; Menoni, Carmen S.; Tomasel, F.G.; Kholi, S.; McCurdy, Patrick R.; Langston, Peter; Ogloza, Albert

doi:10.1117/12.753027

Cited by 14 publications

(10 citation statements)

References 8 publications

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“…Unless stated otherwise the samples were quarter-wave (λ = 800 nm) thick hafnia (HfO 2 ) films deposited on super-polished fused silica substrates using dual ion-beam sputtering (DIBS) with a hafnium-metal target [15]. Figure 2 shows the breakdown fluence as a function of the number of pulses illuminating one and the same sample site at atmospheric pressure (630 Torr at an elevation of 1,600 m) and for 3x10 -7 Torr.…”

Section: Methodsmentioning

confidence: 99%

Femtosecond pulse damage thresholds of dielectric coatings in vacuum

Nguyễn¹,

Emmert²,

Schwoebel³

et al. 2011

Opt. Express

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At 10 -7 Torr, the multiple femtosecond pulse damage threshold, F(∞), is about 10% of the single pulse damage fluence F(1) for hafnia and silica films compared to about 65% and 50%, respectively, at 630 Torr. In contrast, the single-pulse damage threshold is pressure independent. The decrease of F(∞) with decreasing air pressure correlates with the water vapor and oxygen content of the ambient gas with the former having the greater effect. The decrease in F(∞) is likely associated with an accumulation of defects derived from oxygen deficiency, for example vacancies. From atmospheric air pressure to pressures of ~3x10 -6 Torr, the damage "crater" starts deterministically at the center of the beam and grows in diameter as the fluence increases. At pressure below 3x10 -6 Torr, damage is initiated at random "sites" within the exposed area in hafnia films, while the damage morphology remains deterministic in silica films. A possible explanation is that absorbing centers are created at predisposed sample sites in hafnia, for example at boundaries between crystallites, or crystalline and amorphous phases.

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Section: Methodsmentioning

confidence: 99%

Femtosecond pulse damage thresholds of dielectric coatings in vacuum

Nguyễn¹,

Emmert²,

Schwoebel³

et al. 2011

Opt. Express

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“…In this work, we have identified oxygen interstitials. Signatures of these defects were also found in IBS HfO 2 and Ta 2 O 5 and were observed to scale with the thickness of the film [13,17]. However, it is possible that other types of defects, such as oxygen vacancies, could be affecting absorption, and stress in the amorphous Sc 2 O 3 .…”

Section: Discussionmentioning

confidence: 88%

Point defects in Sc₂O₃ thin films by ion beam sputtering

et al. 2014

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We show that the concentration of oxygen interstitials trapped in Sc2O3 films by ion beam sputtering from metal targets can be controlled by modifying deposition conditions. We have identified point defects in the form of oxygen interstitials that are present in Sc2O3 films, in significantly high concentrations, i.e., ∼10(18) cm(-3). These results show a correlation between the increase of oxygen interstitials and the increase in stress and optical absorption in the films. Sc2O3 films with the lowest stress and optical absorption loss at 1 μm wavelength were obtained when using a low oxygen partial pressure and low beam voltage.

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“…The deposition process used for planarization is dual ion beam sputtering (IBS) [21]. The secondary ion source is pointed normal to the substrate and used for etching the deposited silica layers.…”

Section: Experiments and Resultsmentioning

confidence: 99%

Substrate and coating defect planarization strategies for high-laser-fluence multilayer mirrors

et al. 2015

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a b s t r a c t a r t i c l e i n f oAvailable online xxxx Keywords: Nodular defect Laser damage testing 1064-nm laser Nanosecond pulse length Thin film Multilayer mirror Ion beam sputtering PlanarizationPlanarizing or smoothing over nodular defects in multilayer mirrors can be accomplished by a discrete depositand-etch process that exploits the angle-dependent etching rate of optical materials. Typically, nodular defects limit the fluence on mirrors irradiated at 1064 nm with 10 ns pulse lengths due to geometrically-and interference-induced light intensification. Planarized hafina/silica multilayer mirrors have demonstrated N 125 J/cm 2 laser resistance for single-shot testing and 50 J/cm 2 for multi-shot testing for nodular defects originating on the substrate surface. Two planarization methods were explored: thick planarization layers on the substrate surface and planarized silica layers throughout the multilayer in which only the silica layers that are below one half of the incoming electric field value are etched. This paper also describes the impact of planarized defects that are buried within the multilayer structure compared to planarized substrate particulate defects.Published by Elsevier B.V.

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Influence of process conditions on the optical properties HfO 2 /SiO 2 thin films for high power laser coatings

Cited by 14 publications

References 8 publications

Femtosecond pulse damage thresholds of dielectric coatings in vacuum

Femtosecond pulse damage thresholds of dielectric coatings in vacuum

Point defects in Sc₂O₃ thin films by ion beam sputtering

Substrate and coating defect planarization strategies for high-laser-fluence multilayer mirrors

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Influence of process conditions on the optical properties HfO 2 /SiO 2 thin films for high power laser coatings

Cited by 14 publications

References 8 publications

Femtosecond pulse damage thresholds of dielectric coatings in vacuum

Femtosecond pulse damage thresholds of dielectric coatings in vacuum

Point defects in Sc2O3 thin films by ion beam sputtering

Substrate and coating defect planarization strategies for high-laser-fluence multilayer mirrors

Contact Info

Product

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Point defects in Sc₂O₃ thin films by ion beam sputtering