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- Title
Laser Processing of Sub-Wavelength Structures on Sapphire and Alumina for Millimeter Wavelength Broadband Anti-Reflection Coatings.
- Authors
Schütz, Viktor; Young, Karl; Tomotake Matsumura; Hanany, Shaul; Koch, Jürgen; Suttmann, Oliver; Overmeyer, Ludger; Qi Wen
- Abstract
Alumina, sapphire and silicon optical elements are used for the detection of cosmic microwave background radiation with its peak intensity between 0.5 and 10 mm. The reflectivity of such material is high but can be reduced with sub-wavelength structures acting as an anti-reflective coating. Required structure height of over 1 mm can be produced by laser machining. Using ultra-short laser pulses we machined > 1 mm high pyramidal structures on sapphire and alumina. The laser process has been optimized to achieve high area structuring speeds for 1 mm high structures, up to 425 mm2/h. The structured surfaces have been analysed with secondary-electron microscopy, optical confocal microscopy, and transmission spectroscopy in the 100 GHz range and provide an antireflection coating for optical elements in the millimeter wave-length.
- Subjects
SAPPHIRES; ALUMINUM oxide; COSMIC background radiation; ANTIREFLECTIVE coatings; LASER machining; CONFOCAL microscopy
- Publication
Journal of Laser Micro / Nanoengineering, 2016, Vol 11, Issue 2, p204
- ISSN
1880-0688
- Publication type
Article
- DOI
10.2961/jlmn.2016.02.0011