Stress compensation in hafnia/silica optical coatings by inclusion of alumina layers

Oliver, J. B.; Kupinski, Pete; Rigatti, A. L.; Schmid, Ansgar W.; Lambropoulos, John C.; Papernov, Semyon; Kozlov, A. A.; Smith, C.; Hand, Robert D.

doi:10.1364/oe.20.016596

Cited by 51 publications

(27 citation statements)

References 9 publications

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“…When the localized stress exceeds the fracture toughness of the coatings, localized adhesion failure, causing flaking or cracking, will occur. Figure 25 shows the fracture of an electron beam evaporated HfO 2 /SiO 2 coating [67]. A nodular defect in the coating provides an initiation site for tensile stress failure, while tearing of the film is evident within the crack that forms.…”

Section: Mechanical and Environmental Stabilitymentioning

confidence: 99%

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Defect-related properties of optical coatings

Cheng¹,

Wang²

2014

Advanced Optical Technologies

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Defects in optical coatings are a major factor degrading their performance. Based on the nature of defects, we classified them into two categories: visible defects and non-visible defects. Visible defects result from the replication of substrate imperfections or particulates within the coatings by subsequent layers and can increase scattering loss, produce critical errors in extreme ultraviolet lithography, weaken mechanical and environmental stability, and reduce laser damage resistance. Non-visible defects mainly involve a decrease in laser damage resistance but typically have no influence on other properties of optical coatings. In the case of widely used HfO 2 /SiO 2 dielectric coatings, metallic Hf nano-clusters, off-stoichiometric HfO 2 nano-clusters, or areas of high-density electronic defects have been postulated as possible sources for non-visible defects. The emphasis of this review is devoted to discussing localized defect-driven laser-induced damage (LID) in optical coatings used for nanosecond-scale pulsed laser applications, but consideration is also given to other properties of optical coatings such as scattering, environmental stability, etc. The low densities and diverse properties of defects make the systematic study of LID initiating from localized defects time-consuming and very challenging. Experimental and theoretical studies of localized defect-driven LID using artificial defects whose properties can be well controlled are highlighted.

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Section: Mechanical and Environmental Stabilitymentioning

confidence: 99%

“…imaging of the initiation site and crack that forms as a result of the high tensile stress in an evaporated hafnia/silica film (reproduced from Oliver et al[67]). …”

mentioning

confidence: 99%

Defect-related properties of optical coatings

Cheng¹,

Wang²

2014

Advanced Optical Technologies

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“…5(b)]. Alumina has the highest modulus and hardness, which can probably be attributed to the relatively dense film structure without the presence of microcolumnar pores, as indicated by the fact that these films exhibit tensile stresses while allowing for very slow water-diffusion rates [10,11]. Silica, which is also amorphous, has a high hardness (highest along with alumina) but the lowest modulus among the tested films.…”

Section: Resultsmentioning

confidence: 99%

Nano-indentation of single-layer optical oxide thin films grown by electron-beam deposition

2015

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Mechanical characterization of optical oxide thin films is performed using nano-indentation, and the results are explained based on the deposition conditions used. These oxide films are generally deposited to have a porous microstructure that optimizes laser induced damage thresholds, but changes in deposition conditions lead to varying degrees of porosity, density, and possibly the microstructure of the thin film. This can directly explain the differences in the mechanical properties of the film studied here and those reported in literature. Of the four single-layer thin films tested, alumina was observed to demonstrate the highest values of nano-indentation hardness and elastic modulus. This is likely a result of the dense microstructure of the thin film arising from the particular deposition conditions used.

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“…While such deformation is not a major problem for transmitting elements, this becomes a major issue when working with reflected wavefront or with complex optical systems. In order to overcome these limitations, it is either possible to work on the mitigation of individual layer stress level [4,5], the mitigation of stress-induced deformation [6,7] or to perform stress compensation using dual side coatings with different optical functions [8][9][10]. Using the last approach, these coatings may even be designed to be athermal, i.e.…”

Section: Introductionmentioning

confidence: 99%

High-performance thin-film optical filters with stress compensation

Bégou¹,

Lemarchand²,

Lemarquis³

et al. 2019

J. Opt. Soc. Am. A

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We present a thorough description of high performance thin-film optical filters with high flatness. These components can combine several tens or hundreds of layers and are manufactured using plasma-assisted reactive magnetron sputtering. Stress compensation is achieved using dual side coatings with appropriate spectral function. Examples of highly reflecting mirrors at 515 nm with 15 nm flatness peak-to-valley over up to 75 mm diameter aperture, narrow bandpass filters and filters with broadband controlled transmission are described.

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Stress compensation in hafnia/silica optical coatings by inclusion of alumina layers

Cited by 51 publications

References 9 publications

Defect-related properties of optical coatings

Defect-related properties of optical coatings

Nano-indentation of single-layer optical oxide thin films grown by electron-beam deposition

High-performance thin-film optical filters with stress compensation

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