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Diamond optical windows with sub-wavelength surface structures

MetadataDetails
Publication Date2015-06-21
JournalConference on Lasers and Electro-Optics
AuthorsE.V. Anoikin, Alexander Muhr
InstitutionsElement Six (United States)

Over the past few years, diamond has become the material of choice for high power laser windows in multi-kilowatt CO2 laser systems due to diamond’s combination of excellent thermal, mechanical, and optical characteristics. Extreme-ultraviolet lithography is one exciting application for such high power CO2 laser pumps [1]. These windows are typically coated with antireflective (AR) thin films to maximize throughput laser power, increasing transmission at 10 micron wavelength from 71% to 98% or more. As diamond is a remarkably robust material, it is the AR coatings which eventually fail when power density becomes very high. With the industry trending to even more powerful CO2 laser sources and the high costs associated with system downtime, the need for more durable and reliable anti-reflective laser windows is apparent. Surfaces with sub-wavelength structures (SWS) have been proposed as an effective alternative to AR coatings [2], with strong potential for much higher reliability and durability in extremely high power laser applications.