12 December 2018 Laser-induced damage of nodular defects in dielectric multilayer coatings
Jinlong Zhang, Hongfei Jiao, Bin Ma, Zhanshan Wang, Xinbin Cheng
Author Affiliations +
Abstract
Laser-induced damage (LID) of optical coatings has been extensively studied since the invention of the laser. It has been found that the defects, which are unavoidable in real-world optical coatings, are the main reason for triggering laser damage of optical components at low fluences. In particular, embedded nodules in dielectric multilayer coatings are the main limiting defects found in reflective optics operating in nanosecond regimes. During laser irradiation, thermomechanical damage occurs preferentially at nodules because of enhanced energy absorption due to electric-field intensity (EFI) enhancement and the degradation of mechanical stability due to discontinuous boundaries. This report reviews the recent studies of the LID due to nodular defects in dielectric multilayer coatings. First, we present statistical studies on the geometric model and laser damage mechanism of nodules in the real world and introduce the solutions to control the formation of nodules. However, the low density and diverse properties of real nodular defects make the systematic study of LID initiating from localized defects a time-consuming and challenging task. In this regard, experimental and theoretical studies of localized defect-driven LID using artificial defects with properties that can be controlled are highlighted. We also present recent research progress on the damage mechanism of artificial nodules interpreted from aspects of mechanical properties and electric-field enhancement. In addition, approaches for modifying the deposition process or multilayer design are examined to reduce the EFI enhancement in the nodules and to improve the laser damage resistance of near-infrared high-reflective coatings based on the deeper understanding of the underlying physics of the damage process.
© 2018 Society of Photo-Optical Instrumentation Engineers (SPIE) 0091-3286/2018/$25.00 © 2018 SPIE
Jinlong Zhang, Hongfei Jiao, Bin Ma, Zhanshan Wang, and Xinbin Cheng "Laser-induced damage of nodular defects in dielectric multilayer coatings," Optical Engineering 57(12), 121909 (12 December 2018). https://doi.org/10.1117/1.OE.57.12.121909
Received: 2 May 2018; Accepted: 19 November 2018; Published: 12 December 2018
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Cited by 14 scholarly publications.
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KEYWORDS
Laser induced damage

Hybrid fiber optics

Optical coatings

Absorption

Multilayers

Finite-difference time-domain method

Optical engineering

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