Polariscopy with optical near-fields. Issue 9 (7th July 2022)

• Record Type: Journal Article
• Authors: Meguya, Ryu; Ng, Soon Hock; Han, Molong; Anand, Vijayakumar; Katkus, Tomas; Vongsvivut, Jitraporn; Appadoo, Dominique; Nishijima, Yoshiaki; Juodkazis, Saulius; Morikawa, Junko
• Is Part Of: Nanoscale horizons. Volume 7:Issue 9(2022)
• Page Start: 1047
• Page End: 1053
• Publication Date: 2022-07-07
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/d2nh00187j
• Languages: English
• ISSNs: 2055-6756

Abstract

Abstract : Polarisation analysis of light–matter interactions established for propagating optical far-fields is now extended into an evanescent field as demonstrated in this study using an attenuated total reflection (ATR) setup and a synchrotron source at THz frequencies. Abstract : Polarisation analysis of light–matter interactions established for propagating optical far-fields is now extended into an evanescent field as demonstrated in this study using an attenuated total reflection (ATR) setup and a synchrotron source at THz frequencies. Scalar intensity E 2, rather than a vector E -field, is used for absorbance analysis of the s- and p-components of the linearly polarised incident light. Absorption and phase changes induced by the sample and detected at the transmission port of the ATR accessory revealed previously non-accessible anisotropy in the absorption–dispersion properties of the sample probed by the evanescent optical near-field. Mapping of the sample's anisotropy perpendicular to its surface by the non-propagating light field is validated and the cos 2 θ absorbance dependence was observed for the angle θ, where θ = 0° is aligned with the sample's surface. A four-polarisation method is presented for the absorbance mapping and a complimentary retardance spectrum is retrieved from the same measurement of the angular dependence of transmittance in structurally complex poly-hydroxybutyrate (PHB) and poly-l -lactic acid (PLLA) samples with amorphous and banded-spherulite (radially isotropic) crystalline regions. A possibility of all 3D mapping of anisotropy (polarisation tomography) is outlined.