Open AccessBlack and white fused silica: modified sol-gel process combined with moth-eye structuring for highly absorbing and diffuse reflecting SiO2 glass
Author(s) -
Róbert Brunner,
Matthias H. Kraus,
Johannes Hirte,
Zhaolu Diao,
Klaus Weishaupt,
Joachim P. Spatz,
Torsten Harzendorf,
Marcus Trost,
Anne-Sophie Munser,
Sven Schröder,
Michael Baer
Publication year - 2020
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.406150
Subject(s) - materials science , optics , diffuse reflection , specular reflection , diffuse reflectance infrared fourier transform , integrating sphere , structural coloration , micrometer , scattering , mie scattering , light scattering , absorbance , optoelectronics , photonic crystal , chemistry , biochemistry , physics , photocatalysis , catalysis
Diffuse reflecting (white) and highly absorbing (black) fused silica based materials are presented, which combine volume modified substrates and surfaces equipped with anti-reflective moth-eye-structures. For diffuse reflection, micrometer sized cavities are created in bulk fused silica during a sol-gel process. In contrast, carbon black particles are added to get the highly absorbing material. The moth-eye-structures are prepared by block copolymer micelle nanolithography (BCML), followed by a reactive-ion-etching (RIE) step. The moth-eye-structures drastically reduce the specular reflectance on both diffuse reflecting and highly absorbing samples across a wide spectral range from 250 nm to 2500 nm and for varying incidence angles. The adjustment of the height of the moth-eye-structures allows us to select the spectral position of the specular reflectance minimum, which measures less than 0.1%. Diffuse Lambertian-like scattering and absorbance appear nearly uniform across the selected spectral range, showing a slight decrease with increasing wavelength.