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Proceedings Paper

Nanosecond laser-induced damage of high-reflection coatings: NUV through NIR
Author(s): Zhanshan Wang; Hongping Ma; Xinbin Cheng; Jinlong Zhang; Pengfei He; Bin Ma; Hongfei Jiao; Yongjian Tang
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Paper Abstract

Laser-induced damage of high reflection (HR) coatings, working at near ultraviolet (NUV) and near infrared (NIR) regions was investigated. For NIR HR coatings, the nodules still remain the most limiting defects. The E-field intensity (EFI) enhancement in nodules plays a central role for triggering laser-induced damage. We established a simple model for EFI enhancement in nodules using the focusing and light penetrating concept. With the help of finite-difference time domain (FDTD) simulations, we found that refractive indices and nodular geometries affected the focal length as well as the size of focal spots. Furthermore, the angular reflection bandwidth (ARB) of nodules determined the fraction of light that can penetrate to the focal region. For NUV HR coatings, we explored the increase of the laser-induced damage threshold (LIDT) by increasing the incident angle from 0 degrees to 65 degrees for S-polarization. The EFI in a 65 degree HR coating is more than 4 times lower compared to 0 degree HR coatings, which suggests that the LIDT of 65 degree HR coating is much higher compared to 0 degree HR coating. However, we found some contradictory results. For small testing laser beam size with a diameter of 20 μm, the LIDT of 65 degree HR coating is 3.5 times higher compared to a 0 degree HR coating. However, for a large sized testing laser beam with a diameter of 1000 μm, the LIDT of 65 degree HR coating is 2 times lower compared to a 0 degree HR coating. Possible reasons for the observed damage phenomena are discussed.

Paper Details

Date Published: 6 December 2016
PDF: 10 pages
Proc. SPIE 10014, Laser-Induced Damage in Optical Materials 2016, 1001409 (6 December 2016); doi: 10.1117/12.2244567
Show Author Affiliations
Zhanshan Wang, Key Lab. of Advanced Micro-Structure Materials (China)
Tongji Univ. (China)
Hongping Ma, Key Lab. of Advanced Micro-Structure Materials (China)
Tongji Univ. (China)
Xinbin Cheng, Key Lab. of Advanced Micro-Structure Materials (China)
Tongji Univ. (China)
Jinlong Zhang, Key Lab. of Advanced Micro-Structure Materials (China)
Tongji Univ. (China)
Pengfei He, Key Lab. of Advanced Micro-Structure Materials (China)
Tongji Univ. (China)
Bin Ma, Key Lab. of Advanced Micro-Structure Materials (China)
Tongji Univ. (China)
Hongfei Jiao, Key Lab. of Advanced Micro-Structure Materials (China)
Tongji Univ. (China)
Yongjian Tang, Research Ctr. of Laser Fusion (China)


Published in SPIE Proceedings Vol. 10014:
Laser-Induced Damage in Optical Materials 2016
Greg J. Exarhos; Vitaly E. Gruzdev; Joseph A. Menapace; Detlev Ristau; MJ Soileau, Editor(s)

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