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Proceedings Paper

Optical properties of stochastic subwavelength surface structures
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Paper Abstract

High transparent thermoplastics have the capability to put glass out of business, especially in everyday life's optics. Their diverse nature gives rise to different antireflection principles. The reduction of surface reflection losses in polymethylmethacrylate (PMMA) is demonstrated by means of argon/oxygen plasma treatment. Since the presented reduction of reflection occurs in a wide spectral range, the technique may be applied for omnidirectional devices or curved substrates. The etching process creates a self-organized stochastic subwavelength structure at the substrate itself. The decrease in reflection is described by effective medium theory (EMT), converting the surface topology into a depth-dependent filling factor profile. In a second step this nano-scaled structure is used as the initial point for a broadband absorber by coating it with a nontransparent metal layer. A high-efficient absorber can be obtained, if the metal acts as backside coating of the double-sided plasma-treated substrate and steady-going transitions between the materials eliminating the Fresnel reflections. In practice, the magnitude of absorption depends on depth of structure as well as on the complex refractive index of the metal.

Paper Details

Date Published: 20 October 2005
PDF: 10 pages
Proc. SPIE 5965, Optical Fabrication, Testing, and Metrology II, 59651O (20 October 2005); doi: 10.1117/12.624363
Show Author Affiliations
Robert Leitel, Friedrich Schiller Univ. (Germany)
Jörg Petschulat, Fraunhofer Institut für Angewandte Optik und Feinmechanik (Germany)
Antje Kaless, Friedrich Schiller Univ. (Germany)
Ulrike Schulz, Fraunhofer Institut für Angewandte Optik und Feinmechanik (Germany)
Olaf Stenzel, Fraunhofer Institut für Angewandte Optik und Feinmechanik (Germany)
Norbert Kaiser, Fraunhofer Institut für Angewandte Optik und Feinmechanik (Germany)


Published in SPIE Proceedings Vol. 5965:
Optical Fabrication, Testing, and Metrology II
Angela Duparré; Roland Geyl; Lingli Wang, Editor(s)

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