Birefringent optical coatings are shown to have infrared absorbance using polarisation analysis

Birefringent optical coatings are shown to have infrared absorbance using polarisation analysis

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物質理工学院 森川淳子教授Saulius Juodkazis特任教授の国際共著論文

“Anisotropy of 3D Columnar Coatings in Mid-Infrared Spectral Range”

が、Nanomaterials   に掲載されました。(DOI:10.3390/nano11123247

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<Abstract>
Polarisation analysis in the mid-infrared fingerprint region was carried out on thin (∼1 μm) Si and SiO2 films evaporated via glancing angle deposition (GLAD) method at 70 to the normal. Synchrotron-based infrared microspectroscopic measurements were carried out on the Infrared Microspectroscopy (IRM) beamline at Australian Synchrotron. Specific absorption bands, particularly Si-O-Si stretching vibration, was found to follow the angular dependence of ∼cos2θ, consistent with the absorption anisotropy. This unexpected anisotropy stems from the enhanced absorption in nano-crevices, which have orientation following the cos2θ angular dependence as revealed by Fourier transforming the image of the surface of 3D columnar films and numerical modeling of light field enhancement by sub-wavelength nano-crevices.