Open AccessCombined ‘moth-eye’ structured and graded index-layer anti-reflecting coating for high index glasses
Author(s) -
Matthias H. Kraus,
Zhaolu Diao,
Klaus Weishaupt,
Joachim P. Spatz,
Kerstin Täschner,
Hagen Bartzsch,
Ralph Schmittgens,
Róbert Brunner
Publication year - 2019
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.27.034655
Subject(s) - anti reflective coating , refractive index , materials science , optics , substrate (aquarium) , coating , nanopillar , layer (electronics) , transmittance , arc (geometry) , fresnel equations , visible spectrum , optoelectronics , composite material , nanotechnology , geometry , mathematics , oceanography , physics , nanostructure , geology
We present a hybrid antireflective coating (ARC) providing a complete continuous graded refractive index (GRIN) transition from a high-index substrate down to ambient air. The ARC comprises a first GRIN layer of dense silicon-oxy-nitride with a varying, height adjusted material composition. Secondly, a layer of quasi-periodic nanopillars imitating AR-"moth-eye structure" is added to the dense GRIN layer. Demonstrated on a high index glass with a refractive index of n e =1.73 the hybrid GRIN-ARC is applicable to a broad material selection and allows to eliminate any step-like transition up to a refractive index of the substrate of ∼2.0. The ARC offers antireflective properties for large incidence angles and over an extremely broad spectrum ranging from 400 nm up to 2.5 µm. Compared to the sole substrate, the hybrid GRIN-ARC results in an increase of transmittance of more than 10% in the maximum, and more than 6% in the peripheral regions of the spectrum.