Birefringent optical coatings are shown to have infrared absorbance using polarisation analysis
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物質理工学院 森川淳子教授と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
μ
m) 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 ∼
cos
2
θ
, consistent with the absorption anisotropy. This unexpected anisotropy stems from the enhanced absorption in nano-crevices, which have orientation following the
cos
2
θ
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.