Hybrid optical coating design for omnidirectional antireflection purposes

Abstract

We present a new design for an omnidirectional antireflection coating for the visible spectral range. In contrast to classical designs, it combines homogeneous layers and linear gradient index layers into one hybrid design with a full thickness of approximately 500 nm. The coating may be practically produced based on silicon dioxide as low index material and niobium pentoxide as high index material, while intermediate indices may be obtained from corresponding mixtures.

Optical and structural properties of Nb2O5–SiO2 mixtures in thin films

“…In this study, the appropriateness of Lorentz-Lorenz model for calculation of refractive index of Nb 2 O 5 -SiO 2 mixtures in optical characterisation, and therefore the necessity to introduce it into design software [11,12], was tested. Mixture samples of constant refractive index through the layer, with different concentration of SiO 2 to Nb 2 O 5 , were deposited in order to check experimentally the EMT that best describes Nb 2 O 5 -SiO 2 mixtures.…”

Compositional dependence of absorption coefficient and band-gap for Nb2O5–SiO2 mixture thin films

“…This combination of materials has been used for the design [12] and deposition [13] of inhomogeneous coatings for antireflection purposes. The volume fraction of Reflectance and transmittance measurements at normal incidence were performed in the spectral range between 200 and 900 nm with a Perkin Elmer Lambda 900 spectrophotometer.…”

Effective medium theories for composite optical materials in spectral ranges of weak absorption: the case of Nb2O5–SiO2mixtures

“…Experimental A set of Nb 2 O 5 -SiO 2 composite layers was deposited on fused silica (Suprasil) substrates by coevaporation in a Leybold Syrius Pro 1100 system equipped with two electron beam guns and Advanced Plasma source [20]. This combination of materials was used for the design, deposition and characterization of hybrid coatings for antireflection purposes [21][22][23] Reflectance and transmittance measurements at near-normal incidence were performed in the range 200-900 nm with a Perkin Elemer Lambda 900 spectrophotometer. In addition, structural characterization of the layers was carried out using different techniques (X-ray diffraction, transmission electron microscopy and infrared spectroscopy).…”