- Optical properties in the infrared range of the birefringent α-GeO2 single crystal doi link

Auteur(s): Armand Pascale, Hermet P., Bantignies J.-L., Haidoux Abel, Maurin D., Ménart Bertrand, Peña Alexandra, Papet Philippe

(Article) Publié: Materials Research Bulletin, vol. 129 p.110881 (2020)
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DOI: 10.1016/j.materresbull.2020.110881
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The components of the frequency-dependent complex refractive index were determined indirectly for the new non-centrosymmetric α-GeO2 crystal using polarized Fourier transform infrared reflectivity spectra measured in the far- and mid-infrared spectral region at room temperature. All the longitudinal- and transverse-optical infrared active modes with E and A2 symmetry, according to the D3 point group, were identified and localized within the 100-1000 cm-1 range in very good agreement with a previous first-principles based calculation. For the A2- and E-type modes, both the longitudinal- and transverse-optical splitting were detected. The refractive indices no ( E⊥c) and ne (E //c) in the infrared domain present considerably higher values than the ones observed in the visible light range, and the high birefringence would find application in many optical devices.