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Proceedings Paper

Broadband, ultralow reflectance surface structures on silica windows for high-energy laser applications (Conference Presentation)

Paper Abstract

The characteristics of broadband transmission, environmental durability, and laser damage resistance are critical for silica glass exit aperture windows for their use in kW-level, high energy laser systems. The use of conventional antireflective (AR) coatings on windows for high energy lasers operating in the near infrared is impacted by laser induced damage that occurs under high power irradiation as well as the potential for delamination in operational environments. Novel methods for fabricating antireflective surface structures (ARSS) directly on optics have resulted not only in reduced reflection loss, but also in other advantages to AR coatings as well. The ARSS approach involves sub-wavelength surface structures fabricated directly into the actual surface of the window, eliminating the need for a coating of extraneous materials. We will report on results for ARSS fabricated on silica glass windows. Recently we have reported broadband, low reflectance (< 0.02% at 1 µm) for silica glass windows with random ARSS, fabricated using reactive ion etching. These windows have shown remarkably high laser damage thresholds of 100 J/cm2 at 1.06 µm, which is 5x the threshold measured for a conventional AR coating. We will also present results for MILSPEC durability tests on silica windows, both with and without ARSS, for rain and sand erosion as well as salt fog testing, conducted at a government facility. We will also report on scale up of ARSS on silica windows of large sizes (33 cm), making them practical for system implementation.

Paper Details

Date Published: 7 June 2017
PDF: 1 pages
Proc. SPIE 10179, Window and Dome Technologies and Materials XV, 1017905 (7 June 2017); doi: 10.1117/12.2262873
Show Author Affiliations
Lynda E. Busse, U.S. Naval Research Lab. (United States)
Jesse A. Frantz, U.S. Naval Research Lab. (United States)
L. Brandon Shaw, U.S. Naval Research Lab. (United States)
Menelaos K. Poutous, The Univ. of North Carolina at Charlotte (United States)
Ishwar D. Aggarwal, The Univ. of North Carolina at Charlotte (United States)
Jasbinder S. Sanghera, U.S. Naval Research Lab. (United States)

Published in SPIE Proceedings Vol. 10179:
Window and Dome Technologies and Materials XV
Brian J. Zelinski, Editor(s)

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