Coupling effect of subsurface defect and coating layer on the laser induced damage threshold of dielectric coating

Chai, Yaqin; Zhu, Meiping; Yao, Kui; Hu, Qi; Wang, Hu; Sun, Wei; Yu, Zhiqiang; Bai, Zhengyuan; Zhao, Yuanan; Shao, Jianda

doi:10.1117/12.2068034

Cited by 4 publications

(8 citation statements)

References 13 publications

(9 reference statements)

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“…The double-layer coating coated KDP possesses a LIDT of 11.5 J/cm 2 , whereas that coated FSG achieves a higher LIDT of 14.5 J/cm 2 . Such difference in LIDT between coatings on different types of substrates lies in the LIDT of the coating also greatly depends on the surface quality of the substrate . Therefore, the LIDT of the coating on KDP crystal could be even greater than 11.5 J/cm 2 if the surface of the KDP crystal could be specially treated and improved.…”

Section: Resultsmentioning

confidence: 99%

“…Such difference in LIDT between coatings on different types of substrates lies in the LIDT of the coating also greatly depends on the surface quality of the substrate. 33 Therefore, the LIDT of the coating on KDP crystal could be even greater than 11.5 J/cm 2 if the surface of the KDP crystal could be specially treated and improved. Nevertheless, these LIDTs are still much higher than that of PVD coatings.…”

Section: Surface Morphology and Opticalmentioning

confidence: 99%

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Sol–Gel Preparation of Laser Damage Resistant and Moisture-Proof Antireflective Coatings for KDP Crystals

et al. 2018

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Surface fogging induced degradation has been a bottleneck problem in potassium dihydrogen phosphate (KDP) crystals due to they are grown from aqueous solution. In this paper, we developed a facile method to prepare a double-layer antireflective coating with moisture-proof and laser damage resistant properties for KDP crystals. The bottom layer was a poly siloxane coating with dense structure and silanol side groups, while the top layer was a hexamethyl-disilazane (HMDS) modified nanoporous SiO coating. Both of the sols were nonalkaline and nonaqueous to make sure those are harmless to KDP crystals. The double-layer coated KDP crystal exhibited a maximum transmittance of 99.9% with an average increase of transmitted light of 6-7% over the wavelength range between 351 and 1053 nm. After exposure in a 55% relative humidity environment for 6 months, the double-layer HMDS_SiO/PS coating coated KDP crystal displayed nearly the same optical transmittance as the original one, whereas the single-layer HMDS_SiO coated KDP crystal had a transmittance loss of ∼5%. Moreover, the laser-induced damage threshold of the double-layer coating on KDP crystal reached 11.5 J/cm (355 nm, 3 ns). This multifunctional antireflective coating not only can be used for KDP crystals, but also can be applied to thermal-sensitive polymeric substrates.

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Section: Resultsmentioning

confidence: 99%

Section: Surface Morphology and Opticalmentioning

confidence: 99%

Sol–Gel Preparation of Laser Damage Resistant and Moisture-Proof Antireflective Coatings for KDP Crystals

et al. 2018

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“…Microscale pits were precisely fabricated by a femtosecond laser platform, details of which are reported elsewhere1617. A Ti:sapphire laser system with an operating wavelength of 520 nm, pulse width of 340 fs, and repetition rate of 1 kHz was used.…”

Section: Samples and Experimentsmentioning

confidence: 99%

“…All experiments were conducted on the same group of supersonic cleaned fused silica substrates, which were 50 mm in diameter and 5 mm thick. Microscale pits were precisely fabricated by a femtosecond laser platform, details of which are reported elsewhere 16 17 . A Ti:sapphire laser system with an operating wavelength of 520 nm, pulse width of 340 fs, and repetition rate of 1 kHz was used.…”

Section: Samples and Experimentsmentioning

confidence: 99%

Laser-resistance sensitivity to substrate pit size of multilayer coatings

Chai

Zhu

Wang

et al. 2016

Sci Rep

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Nanosecond laser-resistance to dielectric multilayer coatings on substrate pits was examined with respect to the electric-field (E-field) enhancement and mechanical properties. The laser-induced damage sensitivity to the shape of the substrate pits has not been directly investigated through experiments, thus preventing clear understanding of the damage mechanism of substrate pits. We performed a systematic and comparative study to reveal the effects of the E-field distributions and localized stress concentration on the damage behaviour of coatings on substrates with pits. To obtain reliable results, substrate pits with different geometries were fabricated using a 520-nm femtosecond laser-processing platform. By using the finite element method, the E-field distribution and localized stress of the pitted region were well simulated. The 1064-nm damage morphologies of the coated pit were directly compared with simulated E-field intensity profiles and stress distributions. To enable further understanding, a simplified geometrical model was established, and the damage mechanism was introduced.

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“…For a specified irradiated laser fluence, compared with a high-reflection coating, the laser intensity of a coating with partial or high transmittance is stronger at the substrate–coating interface, and subsurface impurity defects are more likely to cause damage under laser irradiation. In addition, the electron beam deposition process often requires the substrate to be heated, and subsurface impurities can easily migrate to the surface during heating [ 7 , 8 ] . Researchers have simulated the effect of impurity particles on the LIDT of substrates using Mie scattering theory and impurity defect absorption models [ 9 , 10 ] .…”

Section: Introductionmentioning

confidence: 99%

Effect of subsurface impurity defects on laser damage resistance of beam splitter coatings

Zhu

Shi

et al. 2023

High Pow Laser Sci Eng

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The laser-induced damage threshold (LIDT) of plate laser beam splitter (PLBS) coatings is closely related to the subsurface absorption defects of the substrate. Herein, a two-step deposition temperature method is proposed to understand the effect of substrate subsurface impurity defects on the LIDT of PLBS coatings. Firstly, BK7 substrates are heat-treated at three different temperatures. The surface morphology and subsurface impurity defect distribution of the substrate before and after the heat treatment are compared. Then, a PLBS coating consisting of alternating HfO2–Al2O3 mixture and SiO2 layers is designed to achieve a beam-splitting ratio (transmittance to reflectance, s-polarized light) of approximately 50:50 at 1053 nm and an angle of incidence of 45°, and it is prepared under four different deposition processes. The experimental and simulation results show that the subsurface impurity defects of the substrate migrate to the surface and accumulate on the surface during the heat treatment, and become absorption defect sources or nodule defect seeds in the coating, reducing the LIDT of the coating. The higher the heat treatment temperature, the more evident the migration and accumulation of impurity defects. A lower deposition temperature (at which the coating can be fully oxidized) helps to improve the LIDT of the PLBS coating. When the deposition temperature is 140°C, the LIDT (s-polarized light, wavelength: 1064 nm, pulse width: 9 ns, incident angle: 45°) of the PLBS coating is 26.2 J/cm2, which is approximately 6.7 times that of the PLBS coating deposited at 200°C. We believe that the investigation into the laser damage mechanism of PLBS coatings will help to improve the LIDT of coatings with partial or high transmittance at laser wavelengths.

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Coupling effect of subsurface defect and coating layer on the laser induced damage threshold of dielectric coating

Cited by 4 publications

References 13 publications

Sol–Gel Preparation of Laser Damage Resistant and Moisture-Proof Antireflective Coatings for KDP Crystals

Sol–Gel Preparation of Laser Damage Resistant and Moisture-Proof Antireflective Coatings for KDP Crystals

Laser-resistance sensitivity to substrate pit size of multilayer coatings

Effect of subsurface impurity defects on laser damage resistance of beam splitter coatings

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